WASHINGTON—Donald Trump has tapped a longtime critic of heavy regulation to flesh out his new administration’s plans for remaking the financial rule book, including the potential dismantling of much of the Dodd-Frank financial overhaul.

Paul Atkins served as a Republican member of the Securities and Exchange Commission from 2002 to 2008, where he spoke out against big fines for companies, arguing they punish shareholders. Now Mr. Atkins, 58 years old, is the member of the president-elect’s transition team charged with recommending policies on financial regulation, according to current and former regulators briefed on the matter.

Mr. Trump has detailed little about his views on financial regulation beyond his vow to dismantle the 2010 Dodd-Frank law—a campaign promise on which his transition team privately has sought to temper expectations, saying the focus was on rescinding or scaling back individual provisions of the law that Republicans find most objectionable.

The fact that Mr. Trump has turned to Mr. Atkins for recommendations provides an additional window into how the president-elect is likely to govern. Mr. Atkins, too, has repeatedly assailed Dodd-Frank, targeting provisions such as the creation of a systemic-risk council that has the power to designate large financial firms for banklike regulation from the Federal Reserve. Mr. Atkins has said the council will “substitute government judgments for investor judgments, deciding for investors whether a product merits investment.”

An aide to Mr. Atkins referred requests for comment to the Trump transition team, which didn’t immediately comment.