Federline, 28, signed to be toe frontman for the Blue Marlin clothing company of San Francisco's upcoming Five Star Vintage clothing line.
Plans call for retailing the clothing at Macy's, Lord & Taylor and Virgin Mega Stores. A Blue Marlin representative said the company believes Federline will draw in the company's target age group of 16 to 28.
Federline took time from recording an upcoming album to defend himself against allegations that he was a "gold digger," for marrying Spears.
"I've been paying for everything out of my pocket," he told People magazine. "Everything."