Prospectus by Investment Company (Form 497)

Supplement Dated September 29, 2025

To The Prospectus Dated April 28, 2025

JNL^® Series Trust

Please note that the changes below may impact your variable annuity and/or variable life product(s).

Unless otherwise noted, all changes are effective immediately.

Effective August 25, 2025, for the JNL/JPMorgan Managed Conservative Fund, JNL/JPMorgan Managed Moderate Fund, JNL/JPMorgan Managed Moderate Growth Fund, JNL/JPMorgan Managed Growth Fund, and JNL/JPMorgan Managed Aggressive Growth Fund, please delete all references to and information for Silvia Trillo.

Effective August 1, 2025, in the section "Summary Overview of Each Fund," under "Portfolio Management," for the JNL Multi-Manager Small Cap Value Fund, please delete the "Portfolio Managers" table in the entirety and replace with the following:

Effective September 30, 2025, in the section "Summary Overview of Each Fund," under "Portfolio Management," for the JNL/T. Rowe Price Mid-Cap Growth Fund, please delete the "Portfolio Managers" table in the entirety and replace with the following:

¹Effective December 31, 2025, Mr. Berghuis plans to retire from T. Rowe Price and will step down from his role on the Fund, and Ms. Woodruff will continue as the Fund's Chairperson of the Investment Advisory Committee and Mr. Easley will continue as the Fund's Co-Chair of the Investment Advisory Committee.

Effective August 25, 2025, in the section "Summary Overview of Each Fund," under "Portfolio Management," for the JNL/JPMorgan Managed Conservative Fund, JNL/JPMorgan Managed Moderate Fund, JNL/JPMorgan Managed Moderate Growth Fund, JNL/JPMorgan Managed Growth Fund, and JNL/JPMorgan Managed Aggressive Growth Fund, please delete the "Portfolio Managers" table in the entirety and replace with the following:

Effective August 1, 2025, in the section "Additional Information About Each Fund," under "The Adviser, Sub-Advisers and Portfolio Management," subsection, "The Sub-Advisers," for the JNL Multi-Manager Small Cap Value Fund, after the eighteenth paragraph, please add the following:

Todd Mayberry, CFA, is a portfolio manager for River Road's Small Cap Value and Small-Mid Cap Value portfolios. Mr. Mayberry previously served as a senior equity research analyst for River Road. He holds equity in the firm. Prior to joining River Road in 2014, he worked as Senior Associate for PNC's corporate bank. Mr. Mayberry earned a BBA in Finance from the University of Cincinnati. He earned the Chartered Financial Analyst^® designation in 2015 and is a member of the CFA Institute and CFA Society Louisville.

Effective September 30, 2025, in the section "Additional Information About Each Fund," under "The Sub-Adviser and Portfolio Management," for the JNL/T. Rowe Price Mid-Cap Growth Fund, please delete the third through fifth paragraphs in the entirety and replace with the following:

The Fund has an Investment Advisory Committee co-chaired by Brian W.H. Berghuis, Donald Easley, and Ashley Woodruff. Ashley R. Woodruff, CFA, is Chairperson of the Investment Advisory Committee for the JNL/T. Rowe Price Mid-Cap Growth Fund. She is a member of the Mid-Cap Growth, Capital Appreciation, Capital Appreciation Equity ETF, and Institutional Mid-Cap Equity Growth Investment Advisory Committees. She also is a member of the T. Rowe Price Investment Management Investment Steering and ESG Committees. She is a vice president of T. Rowe Price Group, Inc. Ms. Woodruff's investment experience began in 2001. She was with T. Rowe Price from 2007 to 2013, beginning as a research analyst in the T. Rowe Price Associates U.S. Equity Division covering stocks in the consumer sector, and returned in 2018. Prior to returning to T. Rowe Price, Ms. Woodruff was employed by Goldman Sachs as a managing director and portfolio manager from 2013 to 2018. Before joining T. Rowe Price in 2007, Ms. Woodruff was a senior vice president and senior restaurants analyst with Friedman, Billings, Ramsey & Co. and an associate director with Bear Stearns, covering high-growth restaurants. Ms. Woodruff earned a B.A., magna cum laude, in economics from Barnard College, Columbia University. She also has earned the Chartered Financial Analyst^® designation.

Brian W.H. Berghuis, CFA, is a portfolio manager for the US Mid-Cap Growth Strategy at T. Rowe Price Investment Management. He is a Vice President of T. Rowe Price Group, Inc., and T. Rowe Price Associates, Inc., and a Portfolio Manager in the Equity Division. He is the Chairman of the T. Rowe Price Mid-Cap Growth Fund's Investment Advisory Committee. He joined the firm in 1985. Brian earned an A.B. from Princeton University and an M.B.A. from Harvard Business School. He is a past President of the Baltimore Security Analysts Society. Brian has also earned the Chartered Financial Analyst accreditation.

Donald J. Easley, CFA, is a portfolio manager for the US Mid-Cap Growth Equity Strategy at T. Rowe Price Investment Management. He is a member of the Mid-Cap Growth, Institutional Mid-Cap Equity Growth, Capital Appreciation, and Capital Appreciation Equity ETF Investment Advisory Committees, and a member of the T. Rowe Price Investment Management Investment Steering Committee. Mr. Easley also is a vice president of T. Rowe Price Group, Inc. Mr. Easley's investment experience began in 1999, and he has been with T. Rowe Price since 2000, beginning in the T. Rowe Price Associates U.S. Equity Division as an analyst covering technology stocks, then as a co-portfolio manager for the Diversified Mid-Cap Growth Fund. Prior to this, he was employed by The Bank of New York as a credit analyst. Mr. Easley earned a B.A. in economics from Swarthmore College and an M.B.A. in finance and accounting from the University of Chicago. He also has earned the Chartered Financial Analyst^® designation.

Effective August 25, 2025, in the section, "Additional Information About Each Fund," under "The Adviser, Sub-Adviser and Portfolio Management," subsection, "The Sub-Adviser," for the JNL/JPMorgan Managed Conservative Fund, JNL/JPMorgan Managed Moderate Fund, JNL/JPMorgan Managed Moderate Growth Fund, JNL/JPMorgan Managed Growth Fund, and JNL/JPMorgan Managed Aggressive Growth Fund, after the second paragraph, please add the following:

Morgan Moriarty, CFA, Executive Director, is a Portfolio Manager in Multi-Asset Solutions based in New York. An employee since 2011, Ms. Moriarty focuses on portfolio construction, manager selection, and driving global tactical asset allocation (GTAA) decisions across a range of multi-asset class investment solutions. Ms. Moriarty is the key portfolio manager on mandates such as New York's 529 Advisor-Guided College Savings Age-Based and Asset Allocation portfolios, and the JPMorgan Diversified Fund. Ms. Moriarty holds a B.S. in Business Administration with majors in finance and entrepreneurship and a minor in psychology from the University of Dayton. She is a CFA charterholder.

In the section, "Management of the Trust," under "Redemption of Fund Shares," please delete the fifth paragraph in the entirety and replace with the following:

Redemptions will generally be in the form of cash, although a Fund reserves the right to redeem in kind from or to another Fund or an unaffiliated fund. If a Fund redeems shares in kind from another Fund or from an unaffiliated fund, it may bear transaction costs and will bear market risks until such time as such securities are converted to cash.

This Supplement is dated September 29, 2025.

				Performance Fee Accounts
Portfolio Manager	Category of Account	# of Accounts	AUM	# of Accounts	AUM
Gary Herbert, CFA	Other Registered Investment Companies	12	$20.79 billion	0	$0
	Other Pooled Vehicles	17	$27.88 billion	0	$0
	Other Accounts	5	$5.54 billion	1	$3.17 billion
Morgan Moriarty, CFA	Other Registered Investment Companies	10	$12.48 billion	0	$0
	Other Pooled Vehicles	4	$1.83 billion	0	$0
	Other Accounts	46	$14.14 billion	2	$3.47 billion

Security Ownership of Portfolio Managers	None	$1- $10,000	$10,001- $50,000	$50,001- $100,000	$100,001- $500,000	$500,001- $1,000,000	Over $1,000,000
Gary Herbert, CFA	X
Morgan Moriarty, CFA	X

				Performance Fee Accounts
Portfolio Manager	Category of Account	# of Accounts	AUM	# of Accounts	AUM
J. Justin Akin	Other Registered Investment Companies	5	$2.5 billion	0	$0
	Other Pooled Vehicles	10	$508 million	0	$0
	Other Accounts	32	$2.23 billion	2	$215 million
R. Andrew Beck	Other Registered Investment Companies	6	$2.55 billion	0	$0
	Other Pooled Vehicles	10	$508 million	0	$0
	Other Accounts	35	$2.86 billion	2	$215 million
Todd Mayberry, CFA	Other Registered Investment Companies	5	$2.5 billion	0	$0
	Other Pooled Vehicles	10	$508 million	0	$0
	Other Accounts	32	$2.23 billion	2	$215 million

Security Ownership of Portfolio Managers	None	$1- $10,000	$10,001- $50,000	$50,001- $100,000	$100,001- $500,000	$500,001- $1,000,000	Over $1,000,000
J. Justin Akin	X
R. Andrew Beck	X
Todd Mayberry, CFA	X