Barney Frank, a key architect of financial-crisis era legislation that reshaped the financial industry, is joining a bank board.

Retired House Democrat Mr. Frank, one of the namesakes of the 2010 Dodd-Frank financial-reform law, was appointed to the board of directors of New York-based Signature Bank on Wednesday.

Signature is a $29 billion bank that primarily works with privately-owned businesses. The 14-year old bank has been growing rapidly and performing well at a time when other banks have struggled. Last quarter it posted its 22nd consecutive quarter of record earnings.

“I like this business model in particular,” Mr. Frank said in an interview. “They don’t get involved with exotic derivatives and credit default swaps.” He also described himself as “very supportive of banking.”

Mr. Frank retired from Congress in January 2013 and is now an author, NBC contributor and public speaker, according to his Twitter profile. He said this is his first board appointment. “I was flattered to be asked,” he said.