MCKESSON CORP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No. )

McKESSON CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Focus on People and Culture

Our Leadership Prescription brings clarity to how we show up — with purpose, speed and heart. A shared framework built for a world moving at digital speed, uniting our I 2 CARE values and LEADRx behaviors to strengthen how we are Advancing Health Outcomes for All®.

McKesson’s Leadership Prescription

I²CARE represents McKesson’sshared valuesand defines who we are at our core. These values have guided McKesson for decades and continue to serve as the cultural foundation for everything we do.

LEADRx defines theleadership behaviors expected of everyone at McKesson, regardless of level. Leadership is not defined by position — it is defined by behavior.

Integrity

Inclusion

Customer-First

Accountability

Respect

Excellence

Create the future

Make bold moves

Move at the pace of possibility

Deliver results that matter

Build future-ready teams

Lead with purpose and humility

A Letter From Our Board Chairand Lead Independent Director

June 12, 2026

Dear Fellow Shareholders,

On behalf of our Board of Directors, we thank you for your investment in and support of McKesson. Fiscal year 2026 was a strong year for the Company, and we also thank Team McKesson for its unwavering commitment to excellence and innovation. Ahead of the Annual Meeting, we reflect on McKesson’s continued progress.

New Board Leadership

At this year’s Annual Meeting, Donald R. Knauss will conclude his service on our Board upon reaching the Board’s tenure and age limits. We thank Don for his leadership and valued contributions over twelve years of dedicated service to McKesson and wish him well.

This year marks an evolution in our Board leadership structure. Brian S. Tyler, who has served as McKesson’s Chief Executive Officer since 2019 and has led the Company’s transformation into a diversified healthcare services leader, assumed the additional role of Chair of the Board, effective May 1, 2026. The independent directors also appointed Dominic J. Caruso as Lead Independent Director, bringing significant financial and governance expertise to the role, including from his tenure as Chief Financial Officer of Johnson & Johnson. As Lead Independent Director, Dominic provides independent Board leadership and oversight.

The Board believes this leadership structure best serves McKesson and its shareholders at this time. As we execute the separation of the Medical-Surgical business and sharpen our focus on the strategic initiatives that will define McKesson’s next chapter, Brian’s proven leadership and the Board’s commitment to independent perspectives give us confidence in our ability to advance our strategy with clarity and momentum.

Our Leadership Prescription

The Board maintains active oversight of culture and talent development, recognizing that how McKesson’s people lead is fundamental to how the Company performs. Earlier this year, McKesson introduced LEADRx, as part of its Leadership Prescription, a new framework designed to unlock our team’s full potential to meet the speed, complexity and expectations of our customers, patients and partners. Along with our I 2 CARE values, LEADRx strengthens how we support our purpose of Advancing Health Outcomes for All® through the following key leadership behaviors:

•Create the future: Set direction, stay curious, connect to what’s next

•Make bold moves: Decide with courage using data, digital insight and judgment

•Move at the pace of possibility: Prioritize, adapt, remove barriers

•Deliver results that matter: Drive value, own outcomes, follow through

•Build future-ready teams: Grow talent and build future skills in others

•Lead with purpose and humility: Build trust, seek perspectives, elevate others

With proven leadership and strong independent oversight, we are confident in our ability to deliver on our strategy.

A Letter From Our Board Chair and Lead Independent Director

The Board believes that embedding these leadership behaviors into how McKesson operates will enhance the Company’s talent pipeline, reinforce a culture of accountability and position the Company to execute effectively in a dynamic environment.

Strong Board Oversight Practices

Our Board brings a breadth of experience spanning healthcare, technology, finance, public policy and beyond that is directly relevant to the challenges and opportunities ahead. Central to how we apply that experience is our commitment to proactive shareholder engagement. We believe that listening to and incorporating shareholder perspectives is critical to driving long-term growth and value. Over the past year, management and members of our Board reached out to shareholders representing approximately 60% of our outstanding common stock and they engaged with shareholders representing approximately 46% of our outstanding common stock on topics including Board composition and refreshment, executive compensation and oversight of emerging areas such as artificial intelligence (AI).

Over the last year, our Board has devoted particular focus to AI, both the opportunity it presents and related governance considerations. Our Board oversees McKesson’s use of AI across key priorities, including improving the employee experience, enhancing the customer and patient experience, and driving enterprise efficiency. Through regular discussions with management, we have heard that AI tools are streamlining prior authorization workflows and reducing administrative burden at healthcare practices, while supply chain applications are improving forecast accuracy, disruption prediction and fraud detection. We are proud that McKesson was recognized as one of America’s Most Innovative Companies by Fortune in 2025.

Thank You

On behalf of our Board of Directors, we thank you for your continued trust and support. As McKesson continues to execute its strategic priorities, the Company is well positioned to deliver long-term value for its shareholders.

Your vote is very important to us. We encourage you to review our proxy statement and annual report ahead of the Annual Meeting on July 22, 2026, and support the Board’s voting recommendations.

Notice of 2026 Annual Meeting of Shareholders To Be Held on July 22, 2026

We also will conduct such other business as may properly be brought before the meeting.

You will be able to attend the Annual Meeting online, vote and submit questions during the meeting by visitingwww.virtualshareholdermeeting.com/MCK2026 and entering the 16-digit control number included in our Notice Regarding the Availability of Proxy Materials, voting instructions form or proxy card. Online access to the audio webcast will open approximately 15 minutes prior to the start of the Annual Meeting to allow time for you to log in and test the computer audio system.

On or about June 12, 2026, we began delivering proxy materials to all shareholders of record at the close of business on May 27, 2026. The mailing address of our principal executive offices is McKesson Corporation, 6555 State Highway 161, Irving, Texas 75039.

By Order of the Board of Directors

Saralisa C. Brau

Corporate Secretary

June 12, 2026

VOTING METHODS

Important Notice Regarding the Availability of Proxy Materials for the 2026 Annual Meeting of Shareholders to be held on July 22, 2026. Our 2026 proxy statement and annual report are available free of charge at proxyvote.com.