August 31, 2020 Dear Fellow Shareholder: You are cordially invited to attend the 2020 Annual General Meeting of Shareholders of Seagate Technology plc, which will be held at 5:00 p.m. Irish Standard Time on Thursday, October 22, 2020, at 10 Earlsfort Terrace, Dublin 2, D02 T380, Ireland. Due to public health concerns and continuing uncertainty in connection with COVID-19, this year we also are offering you the opportunity to virtually join the Annual General Meeting via live webcast over the Internet at 5:00 p.m. Irish Standard Time (12:00 p.m. Eastern Daylight Time). You may virtually join the Annual General Meeting and submit your questions during the meeting by visiting www.virtualshareholdermeeting.com/STX2020. In accordance with Irish law, we are required to have a principal meeting place, which is a physical location, where shareholders may attend the Annual General Meeting in person and vote. However, in light of public health concerns and travel recommendations and restrictions, we strongly advise shareholders not to attend in person at the principal meeting place, and ask that shareholders join the Annual General Meeting virtually instead. Shareholders joining virtually will not be able to vote at the meeting. Your vote is important. We encourage shareholders to cast their votes in advance of the Annual General Meeting, whether they plan to attend in person or join virtually. We continue to monitor COVID-19 developments and other circumstances. Should we determine that alternate Annual General Meeting arrangements may be advisable or required, such as changing the date, time or location of the Annual General Meeting, we will announce our decision by press release, post additional information at investors.seagate.com, and make a public filing with the U.S. Securities and Exchange Commission. Please monitor the “Events” tab of investors.seagate.com regularly, as circumstances may change upon short notice. Details of the business to be presented at the meeting may be found in the Notice of 2020 Annual General Meeting of Shareholders and the Proxy Statement accompanying this letter. We urge you to read the Proxy Statement carefully and use one of the specified methods of voting to ensure that your shares will be voted at the 2020 Annual General Meeting. On behalf of the Board of Directors of Seagate Technology plc, we thank you for your continued support. Sincerely, Michael R. Cannon William D. Mosley Chair of the Board Chief Executive Officer and Director 2020 NOTICE OF MEETING AND PROXY STATEMENT SEAGATE TECHNOLOGY PUBLIC LIMITED COMPANY NOTICE OF 2020 ANNUAL GENERAL MEETING OF SHAREHOLDERS The 2020 Annual General Meeting of Shareholders (the “2020 AGM”) of Seagate Technology plc (“Seagate” or the “Company”), a company incorporated under the laws of Ireland with its principal executive offices at 38/39 Fitzwilliam Square, Dublin 2, D02 NX53, Ireland, will be held on Thursday, October 22, 2020, at 5:00 p.m. Irish Standard Time, at 10 Earlsfort Terrace, Dublin 2, D02 T380, Ireland. Due to public health concerns and continuing uncertainty in connection with COVID-19, this year we are also offering you the opportunity to join the 2020 AGM virtually via live webcast over the Internet. We encourage you to use this feature rather than attending the 2020 AGM in person. Those participating virtually can join and submit questions via the Internet during the 2020 AGM by accessing www.virtualshareholdermeeting.com/STX2020. However, shareholders joining virtually will not be able to vote at the meeting. We encourage shareholders to cast their votes prior to the 2020 AGM by one of the methods described in the accompanying Proxy Statement to ensure that your shares will be voted at the 2020 AGM, even if you plan to attend in person or join virtually. The Company is monitoring COVID-19 developments and other circumstances, as well as guidance issued by the Irish Health Service Executive (“HSE”), the Irish government, the U.S. Centers for Disease Control and Prevention, and the World Health Organization. We have implemented, and will continue to implement, the measures advised by the HSE to minimize the spread of COVID-19, including in respect of the 2020 AGM. Should we determine that alternative 2020 AGM arrangements may be advisable or required, such as changing the date, time or location of the 2020 AGM, we will announce our decision by press release, post additional information at investors.seagate.com, and make a public filing with the U.S. Securities and Exchange Commission (“SEC”); such notifications will be in accordance with Irish and other applicable laws, rules and regulations. Please monitor the “Events” tab of investors.seagate.com regularly, as circumstances may change upon short notice. The purposes of the 2020 AGM, which are more completely described in the accompanying Proxy Statement, are: General Proposals: 1. By separate resolutions, to elect as directors the following incumbent directors who shall retire in accordance with the Constitution and, being eligible, offer themselves for election and to elect as a director (the “Director Nominees”): (a) Mark W. Adams (b) Judy Bruner (c) Michael R. Cannon (d) William T. Coleman (e) Jay L. Geldmacher (f) Dylan Haggart (g) Stephen J. Luczo (h) William D. Mosley (i) Stephanie Tilenius (j) Edward J. Zander 2. Approve, in an advisory, non-binding vote, the compensation of the Company’s named executive officers (“Say-on-Pay”). 3. Ratify, in a non-binding vote, the appointment of Ernst & Young LLP as the independent auditors of the Company for the fiscal year ending July 2, 2021 (“fiscal year 2021”), and authorize, in a binding SEAGATE TECHNOLOGY PLC 2020 Proxy Statement 2020 NOTICE OF MEETING AND PROXY STATEMENT vote, the Audit Committee (“Audit Committee”) of the Company’s Board of Directors (the “Board”) to set the auditors’ remuneration. Irish Law Proposal: The Irish Companies Act 2014, as amended (the “Irish Companies Act”) obligates us to propose certain matters to shareholders for approval that would generally not be subject to periodic approval by shareholders of companies incorporated in the United States but are considered routine items for approval by shareholders of companies incorporated in Ireland. 4. Determine the price range at which the Company can re-allot shares that it acquires as treasury shares. Other: 5. Conduct such other business properly brought before the meeting. The Board recommends that you vote “FOR” each director nominee included in Proposal 1 and “FOR” each of Proposals 2 through 4. The full text of these proposals is set forth in the accompanying Proxy Statement. Proposals 1, 2, and 3 are ordinary resolutions, requiring the approval of a simple majority of the votes cast at the meeting. Proposal 4 is a special resolution, requiring the approval of not less than 75% of the votes cast at the meeting. Only shareholders as of the close of business on August 24, 2020 (“Record Date”) are entitled to receive notice of and to vote at the 2020 AGM. If you are a shareholder as of the close of business on the Record Date, you may attend, speak and vote at the 2020 AGM or you may appoint a proxy or proxies to attend, speak and vote on your behalf. A proxy need not be a shareholder. If you wish to appoint as proxy any person other than the individuals specified on the proxy card, please contact the Company Secretary at our registered office and also note your nominated proxy must attend the 2020 AGM in Dublin in person in order for your votes to be cast. Whether or not you plan to attend the meeting or join virtually, we encourage you to please read the accompanying Proxy Statement and submit your proxy as soon as possible, so that your shares may be represented at the 2020 AGM in Dublin. You may vote by proxy by using the Internet, calling by telephone, or completing, signing and returning your proxy card by mail by no later than 6:59 p.m. Eastern Daylight Time (11:59 p.m. Irish Standard Time) on October 21, 2020 (or, if you are a beneficial owner, such earlier time as your bank, broker- dealer, brokerage firm, or nominee may require). Instructions on how to submit your proxy are set forth in the accompanying Proxy Statement. If you have any questions about the meeting or require assistance, please call Georgeson LLC, our proxy solicitor, at +1 781 575 2137 or at + 1 800 891 3214 (toll-free within the United States). During the meeting, following a review of the Company’s affairs, management will also present Seagate’s Irish statutory financial statements for the fiscal year ended July 3, 2020 and the reports of the directors and auditors thereon. By order of the Board, Katherine E. Schuelke Senior Vice President, Chief Legal Officer and Company Secretary August 31, 2020 SEAGATE TECHNOLOGY PLC 2020 Proxy Statement 2020 NOTICE OF MEETING AND PROXY STATEMENT IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL GENERAL MEETING OF SHAREHOLDERS TO BE HELD ON OCTOBER 22, 2020 We will rely on the SEC rule that allows companies to furnish proxy materials over the Internet instead of mailing printed copies of those materials to each shareholder. As a result, we are sending our shareholders a Notice of Internet Availability of Proxy Materials (the “Notice”) instead of a paper copy of our Proxy Statement, including our Irish statutory financial statements for the Company’s fiscal year ended July 3, 2020 (“fiscal year 2020”) and any other appendices thereto, the proxy card and our Annual Report on Form 10-K for fiscal year 2020 (collectively, the “Proxy Materials”). The Notice also contains instructions on how to request a paper or email copy of the Proxy Materials.