SEC Form 6-K filed by KT Corporation

1Q25 Earnings Release

Disclaimer This presentation has been prepared by KT Corp.(the “Company”) in accordance with K-IFRS. This presentation contains forward-looking statements, which are subject to risks, uncertainties, and assumptions. This presentation is being presented solely for your information and is subject to change without notice. No presentation or warranty, expressed or implied, is made and no reliance should be placed on the accuracy, actuality, fairness, or completeness of the information presented. st The Company has applied new accounting standard of K-IFRS 1115 as of Jan 1 , 2018 and K-IFRS st 1116 ‘Leases’ as of Jan 1 , 2019. There are no obligation to apply the new standard to previous financial statements. If you have any questions related to this material, please contact the IR department. Tel: +82-70-4193-4036 2

Contents 1 1Q25 Highlights 2 Financial Highlights 3 Business Overview 4 Appendix

1 1Q25 Highlights Strong OP growth driven by CT/AX and real estate development project* Financials (Unit: KRW) Cons. Sep. Revenue Revenue 6,845.1bn (YoY +2.9%) 4,682.0bn (YoY -0.3%) Operating Operating 688.8bn (YoY +36.0%) 400.1bn (YoY +1.6%) Profit Profit * Through recognition of apartment sales revenue Shareholder return Announce KRW 600 Share Buyback Dividend 1Q25 KRW 250bn 2 dividend amount 3 1 per share & Cancellation Procedure Dividend (Value-up plan) prior to record date (YoY +20%) 1)Record date : ‘25.03.31 , 2)Cancellation TBC, considering foreign limits, 3)Quarterly dividend(2Q25~) Business Strategy AX Business Growth Value-Up Plan Execution * ✓ Launch of Korean AI model and KT SPC based ✓ Accelerate AICT Transformation - AI/IT rev. up YoY +10.2% on Microsoft partnership (‘25.06~) * Secure Public Cloud ✓ Liquidate non-core assets ’25.03 ’25.04 - Completed the sale of Initech , Play D ✓ Strategic partnership with Palantir(‘25.03) ✓ Media business innovation based on AI ✓ Streamline low-margin business(20 units) - Accelerating AX with media AI Agent, AI Studio Lab 4

Contents 1 1Q25 Highlights 2 Financial Highlights 3 Business Overview 4 Appendix

K-IFRS / Consolidated 1 Income Statement • Revenue +2.9% YoY driven by growth in Telco, real estate, and cloud/DC businesses • OP +36.0% YoY reflecting KT Group-wide efforts for profitability and gains from real estate sales (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY Operating Revenue 6,654.6 6,575.6 6,845.1 4.1% 2.9% Service Revenue 5,722.7 5,754.7 5,700.4 -0.9% -0.4% Sale of goods 931.9 820.9 1,144.7 39.4% 22.8% Operating Expense 6,148.1 7,230.7 6,156.3 -14.9% 0.1% Turned to 506.5 -655.1 688.8 36.0% Operating Income Profit Margin 7.6% -10.0% 10.1% 20.1%p 2.5%p 1 Margin 8.9% -11.4% 12.1% 23.5%p 3.2%p Turned to Non-op. Income/Loss 22.5 -354.9 23.1 2.5% Profit Turned to Income before taxes 529.0 -1,010.1 711.8 34.6% Profit Turned to Net Income 393.0 -769.6 566.8 44.2% Profit 5.9% -11.7% 8.3% 20.0%p 2.4%p Margin EBITDA 1,480.2 318.0 1,657.4 421.2% 12.0% Margin 22.2% 4.8% 24.2% 19.4%p 2.0%p 1 1) OP Margin = Operating Income/Service Revenue 6

K-IFRS / Consolidated 2 Operating Expenses • OP. expenses remained flat, as key costs such as depreciation and selling expenses remained stable (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY Operating Expenses 6,148.1 7,230.7 6,156.3 -14.9% 0.1% 1,100.9 2,189.6 1,121.8 -48.8% 1.9% Labor Cost General Expense 2,674.2 2,791.2 2,655.8 -4.8% -0.7% - Depreciation 973.7 973.1 968.7 -0.5% -0.5% 726.5 667.5 798.3 19.6% 9.9% Cost of Service Selling Expense 599.6 608.4 598.0 -1.7% -0.3% Cost of Goods sold 1,046.9 974.0 982.3 0.9% -6.2% [Selling Expense (KT Separate)] (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY Selling Expense 620.6 630.7 625.5 -0.8% 0.8% 7

K-IFRS / Consolidated 3 Balance Sheet • Net Debt/equity ratio +6.1%p QoQ following an increase borrowings across the subsidiaries (Unit: KRW bn) Mar 31, 2024 Dec 31, 2024 Mar 31, 2025 QoQ YoY Assets 42,710.0 41,880.0 42,185.6 0.7% -1.2% 3,000.7 3,716.7 3,133.0 -15.7% 4.4% Cash & Cash equivalents Liabilities 24,127.8 23,883.4 23,847.3 -0.2% -1.2% 10,151.4 10,520.7 11,169.5 6.2% 10.0% Borrowings Equity 18,582.2 17,996.5 18,338.3 1.9% -1.3% Capital Stock 1,564.5 1,564.5 1,564.5 0.0% 0.0% Net Debt 7,150.7 6,804.0 8,036.5 18.1% 12.4% Debt / Equity 129.8% 132.7% 130.0% -2.7%p 0.2%p Net Debt / Equity 38.5% 37.8% 43.8% 6.0%p 5.3%p 134.9% 132.7% 131.1% 130.1% 129.8% 130.0% 127.3% 127.0% 124.8% 122.5% 122.8% 121.5% 115.4% D 부채비율 ebt/Equity 46.6% 순부채비율 44.6% 43.8% Net Debt/Equity 42.9% 41.0% 40.6% 39.5% 37.4% 38.5% 38.5% 37.8% 33.5% 30.3% 8 1Q22 2Q22 3Q22 4Q22 1Q23 2Q23 3Q23 4Q23 1Q24 2Q24 3Q24 4Q24 1Q25

K-IFRS / Separate and major subsidiaries 4 CAPEX • 1Q25 Total CAPEX Execution: KRW 300.0bn (KT Separate), KRW 351.8bn (Major Subsidiaries) (Unit: KRW bn) 3,534 3,319 3,124 813 907 824 ■ Major Subsidiaries’ CAPEX Includes Finance, Media, Cloud/DC, 2,721 Real Estate, etc. 2,412 2,300 652 ■ KT Separate CAPEX 352 300 Access network, Backbone Network, 2022 2023 2024 1Q25 B2B and etc. KT 주요 그룹사 Major Subsidiaries 9

Contents 1 1Q25 Highlights 2 Financial Highlights 3 Business Overview 4 Appendix

K-IFRS / Separate 1 KT - Wireless • Wireless service revenue +1.6% YoY with increased 5G penetration (78.9%) and MVNO revenue • Expanded customer choice with mid-tier and online-only plans, and strengthened online marketing (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY Wireless 1,736.5 1,717.8 1,753.1 2.1% 1.0% Wireless Service 1,649.8 1,648.8 1,676.8 1.7% 1.6% Interconnection 86.7 69.0 76.3 10.5% -12.0% Wireless Subscribers (Unit: Thousands) 26,445 26,132 25,199 24,834 24,904 10,539 10,400 10,251 9,948 10,093 2,815 2,969 Handset(5G) 3,184 3,519 3,364 Handset(5 (ex G c.외 5G )) 5,832 5,581 4,562 4,313 4,276 2nd device & IoT MVNO 7,203 7,182 7,259 7,091 7,134 1Q24 2Q24 3Q24 4Q24 1Q25 11

K-IFRS / Separate 2 KT - Fixed Line • Broadband revenue +1.3% YoY, due to increase in GiGA subscribers and new value-added services • Media revenue +0.1% YoY, following a continued subscriber shift to premium plans and to upgraded set-top boxes (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY Fixed Line 1,322.4 1,317.1 1,311.7 -0.4% -0.8% Broadband 620.8 625.4 628.7 0.5% 1.3% Media 518.6 523.2 519.2 -0.8% 0.1% Home Telephony 183.0 168.6 163.8 -2.8% -10.5% Broadband Subscribers IPTV Subscribers (Unit: Thousands) (Unit: Thousands) Subscribers GiGA (%) 9,600 9,500 9,984 9,956 9,438 9,928 9,899 9,862 9,300 9,200 69.4% 69.2% 68.9% 68.7% 68.5% 1Q24 2Q24 3Q24 4Q24 1Q25 1Q24 2Q24 3Q24 4Q24 1Q25 12

K-IFRS / Separate 3 KT - B2B Services • B2B Service revenue -0.3% YoY, owing to continued streamlining of low-margin businesses • AI/IT revenue +11.9% YoY, sustaining strong double-digit growth trend (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY B2B Service 895.0 856.5 892.2 4.2% -0.3% Corp. Broadband/Data Revenue Revenue of AI/IT (Unit: KRW bn) (Unit: KRW bn) 335.4 327.0 323.5 324.2 325.1 YoY +3.7% 312.2 279.0 280.7 259.9 254.8 YoY +10.2% 1Q24 2Q24 3Q24 4Q24 1Q25 1Q24 2Q24 3Q24 4Q24 1Q25 ※ Corp. Broadband/Data rev includes: ※ AI/IT rev includes: Leased line, Kornet, VPN, Global data AX platform-based including AICC, IoT, Multi/Hybrid Cloud, and Smart Mobility 13

K-IFRS / Consolidated(each subsidiary) 4 Major Subsidiaries • BC Card revenue -6.8% YoY, as card transactions slowed in response to broader economic uncertainty • kt cloud, revenue +42.2% YoY, supported by increased DC usage from global clients and momentum in D&B* *Design & Build operations Revenue of Major Subsidiaries (consolidated) (Unit: KRW bn) 1Q24 4Q24 1Q25 QoQ YoY BC Card 935.6 961.1 872.0 -9.3% -6.8% Kt skylife 254.4 257.0 242.9 -5.5% -4.5% * Content Subsidiaries 138.6 163.4 143.7 -12.1% 3.7% kt cloud 175.2 221.0 249.1 12.7% 42.2% kt estate 137.7 174.8 137.3 -21.4% -0.3% *kt nasmedia(PlayD incl.), kt studiogenie(Genie music, Storywiz, and others incl.) (Unit: KRW bn) Subsidiaries’ OP Contribution 288.7 135.1 125.2 112.7 89.9 1Q24 2Q24 3Q24 4Q24 1Q25 14

Contents 1 1Q25 Highlights 2 Financial Highlights 3 Business Overview 4 Appendix

1 K-IFRS Income Statement (Unit: KRW bn) Consolidated 1Q24 2Q24 3Q24 4Q24 1Q25 KT Separate 1Q24 2Q24 3Q24 4Q24 1Q25 4,694.8 4,548.3 4,765.0 Operating revenue 6,654.6 6,546.4 6,654.6 6,575.6 6,845.1 Operating revenue 4,571.6 4,682.0 Service revenue 5,722.7 5,776.6 5,752.0 5,754.7 5,700.4 Service revenue 4,040.6 4,048.0 4,069.0 3,995.8 4,044.5 Sale of goods 931.9 769.8 902.7 820.9 1,144.7 Handset revenue 654.2 500.3 696.0 575.8 637.5 Operating expense 6,148.1 6,052.4 6,190.5 7,230.7 6,156.3 Operating expense 4,301.0 4,189.5 4,426.1 5,316.6 4,281.9 Cost of Service 5,101.2 5,178.9 5,111.6 6,256.7 5,174.0 Cost of Service 3,624.7 3,696.8 3,688.7 4,713.8 3,620.7 540.7 631.3 534.6 Labor cost 1,100.9 1,213.2 1,118.3 2,189.6 1,121.8 Labor cost 1,545.1 460.2 General expense 2,674.2 2,708.3 2,692.6 2,791.2 2,655.8 General expense 1,777.1 1,804.2 1,832.7 1,905.9 1,875.7 673.2 630.6 685.6 Cost of service 726.5 656.6 699.8 667.5 798.3 Cost of service 620.0 647.5 Selling expense 599.6 600.8 600.8 608.4 598.0 Selling expense 633.7 630.7 635.7 642.8 637.4 Cost of Goods sold 974.0 982.3 Cost of Devices sold 676.3 492.6 737.3 602.8 661.2 1,046.9 873.5 1,078.9 393.8 358.8 338.9 Operating income 506.5 494.0 464.1 -655.1 688.8 Operating income -745.0 400.1 N-OP income (loss) 22.5 62.7 45.0 -354.9 23.1 N-OP income (loss) 72.4 50.3 69.2 -101.5 48.2 309.0 260.0 32.5 N-OP income 323.1 325.8 35.8 611.5 199.1 N-OP income 538.7 158.2 N-OP expense 310.9 260.1 -11.1 969.7 167.9 N-OP expense 236.6 209.7 -36.7 673.2 110.0 Equity Method (G/L) 10.2 -3.0 -1.9 3.3 -8.2 Income bf tax 529.0 556.7 509.1 -1,010.1 711.8 Income bf tax 466.1 409.2 408.0 -879.5 448.3 112.1 94.7 98.2 Income tax 136.0 146.2 125.9 -240.4 145.0 Income tax -228.1 82.9 Net income 393.0 410.5 383.2 -769.6 566.8 Net income 354.0 314.5 309.8 -618.5 365.4 NI contribution to KT 375.5 393.0 357.3 -655.6 539.8 EBITDA 1,480.2 1,460.2 1,428.9 318.0 1,657.4 EBITDA 1,199.1 1,162.9 1,144.8 70.4 1,210.6 EBITDA Margin EBITDA Margin 22.2% 22.3% 21.5% 4.8% 24.2% 25.5% 25.6% 24.0% 1.5% 25.9% 16

2 K-IFRS Balance Sheet (Unit: KRW bn) Consolidated 1Q24 2Q24 3Q24 4Q24 1Q25 KT Separate 1Q24 2Q24 3Q24 4Q24 1Q25 Assets 42,710.0 43,144.4 42,750.4 41,880.0 42,185.6 Assets 30,334.8 30,464.8 29,957.1 29,528.9 29,041.0 Current assets 14,997.4 15,175.2 15,197.0 14,251.9 14,458.5 Current assets 7,578.4 7,451.7 7,447.7 6,892.6 7,016.3 Cash & cash equivalents 3,000.7 3,786.7 3,953.9 3,716.7 3,133.0 Cash & cash equi. 1,331.6 1,722.5 1,608.7 1,540.6 1,150.6 Trade & other receivables 4,571.4 4,161.7 4,304.2 3,987.3 4,217.8 Trade & other rec. 3,546.3 3,097.6 3,275.6 2,904.8 3,209.5 310.3 404.1 264.6 Inventories 899.1 964.0 903.2 940.2 853.9 Inventories 224.7 190.2 Other current asset 6,526.2 6,262.7 6,035.7 5,607.8 6,253.8 Other current asset 2,390.2 2,227.5 2,298.8 2,222.5 2,465.9 1,335.4 1,312.5 1,318.3 - Prepaid_Contract cost 1,249.2 1,233.6 1,236.7 1,233.6 1,325.3 - Prepaid_Contract cost 1,308.8 1,405.7 - Contract assets 620.4 611.1 625.6 577.4 597.9 - Contract assets 540.2 548.6 542.0 521.1 521.4 Non-current assets 27,712.6 27,969.2 27,553.4 27,628.0 27,727.1 Non-current assets 22,756.4 23,013.1 22,509.4 22,636.3 22,024.7 Trade & other rec 381.2 398.4 357.0 381.8 336.3 Trade & other rec 298.8 321.1 278.2 309.1 241.1 11,214.3 11,264.4 11,185.6 Tangible assets 14,585.7 14,591.7 14,509.1 14,825.8 14,398.1 Tangible assets 11,477.7 11,068.3 Other current assets 12,745.7 12,979.1 12,687.3 12,420.4 12,992.7 Other current assets 10,281.4 10,472.9 10,116.8 9,953.2 9,856.6 - Prepaid_Contract cost 465.1 471.4 485.2 504.6 462.3 - Prepaid_Contract cost 451.9 453.8 475.3 493.4 454.8 - Contract assets 229.3 226.3 225.3 223.4 208.3 - Contract assets 207.4 204.1 201.7 198.2 182.3 Liabilities 24,127.8 24,162.5 23,564.0 23,883.4 23,847.3 Liabilities 15,335.6 15,166.7 14,513.1 15,108.7 14,409.3 Current liabilities 14,046.1 14,095.2 14,644.5 13,874.7 13,134.6 Current liabilities 7,477.8 7,315.1 8,074.9 7,633.2 7,265.4 Trade & other payables 8,282.4 8,052.3 7,712.9 7,394.8 6,952.5 Trade & other payables 4,864.3 4,694.7 4,421.5 4,585.8 4,258.8 1,914.9 1,789.5 2,860.3 Short-term borrowings 3,538.6 3,595.0 4,358.7 3,904.8 3,649.1 Short-term borrowings 2,434.2 2,263.0 Others 2,225.1 2,447.9 2,572.9 2,575.2 2,533.0 Others 698.5 830.8 793.0 613.2 743.6 227.0 206.9 210.5 - Contract liabilities 239.3 231.2 230.6 226.4 244.1 - Contract liabilities 208.4 217.8 Non-current liabilities 10,081.7 10,067.3 8,919.5 10,008.7 10,712.7 Non-current liabilities 7,857.9 7,851.6 6,438.2 7,475.5 7,144.0 Trade & other payables 554.1 556.1 573.4 578.4 372.4 Trade & other payables 1,074.2 1,063.8 1,010.2 979.4 672.0 5,652.2 5,675.7 4,290.7 Long-term borrowings 6,612.8 6,555.6 5,409.9 6,615.9 7,520.5 Long-term borrowings 5,437.7 5,417.6 Others 2,914.8 2,955.4 2,936.2 2,814.3 2,819.9 Others 1,131.5 1,112.0 1,137.3 1,058.4 1,054.4 - Contract liabilities 48.7 43.6 48.7 46.9 48.4 - Contract liabilities 36.0 26.4 32.9 34.5 37.5 14,999.2 15,298.1 15,444.1 Equity 18,582.2 18,981.9 19,186.4 17,996.5 18,338.3 Equity 14,420.2 14,631.7 Retained earnings 14,361.5 14,452.7 14,675.2 13,779.8 14,197.4 Retained earnings 12,390.5 12,404.2 12,579.2 11,717.9 11,965.0 17

K-IFRS / Separate 3 Subscribers (Unit: Thousands) Wireless Subscribers 1Q 24 2Q 24 3Q 24 4Q 24 1Q 25 QoQ YoY Total 24,834 24,904 25,199 26,132 26,445 1.2% 6.5% - MNO 17,743 17,770 17,997 18,950 19,186 1.2% 8.1% - MVNO 7,091 7,134 7,203 7,182 7,259 1.1% 2.4% 1) 5G Handset 9,948 10,093 10,251 10,400 10,539 1.3% 5.9% 2) Churn rate 1.1% 1.0% 1.0% 1.1% 1.0% 0.1%p -0.1%p 3) 34,560 ARPU (KRW) 34,461 34,507 34,567 34,856 0.8% 1.1% nd 1) 5G Handset : Retroactively applied from 1Q23 based on the change of subscriber disclosure criteria by the MSIT (excludes 5G 2 Device and 5G IoT) 2) Churn rate : Based on MNO subscribers (excludes IoT) 3) ARPU = Wireless revenue* / Wireless subscribers** * Wireless revenue(3G, LTE, 5G incl.): Revenue of Voice/Data usage (Interconnection/Subscription fee exc.), VAS, Contract/ Bundled Discounts, and etc. incl. ** Wireless subscribers: Based on MSIT’s guidelines for average billed subscribers in quarter (IoT/M2M exc.) (Unit: Thousands) Fixed Line Subscribers 1Q 24 2Q 24 3Q 24 4Q 24 1Q 25 QoQ YoY Telephony 11,903 11,748 11,616 11,475 11,320 -1.4% -4.9% - PSTN 8,673 8,526 8,395 8,264 8,122 -1.7% -6.4% - VoIP 3,230 3,222 3,222 3,211 3,198 -0.4% -1.0% Broadband 9,862 9,899 9,928 9,956 9,984 0.3% 1.2% IPTV (GTV+GTS) 9,418 9,423 9,440 9,449 9,438 -0.1% 0.2% ※ Number of IPTV subscribers above differs from MSIT figures that follow the IPTV law - Number of KT pay TV subscribers in 2H 2024 is 8,852,093 (6-month average) 18