Born in Perth Amboy, New Jersey, he grew up there and in the adjoining township of Woodbridge. He attended Rutgers Preparatory School, graduating in the class of 1963. A center on the basketball team, he made All-State in his senior year and was inducted into the Rutgers Prep Athletic Hall of Fame in 1993. He studied at the Wharton School of the University of Pennsylvania, graduating in 1967. He was a reporter and then managing Editor of the campus newspaper, The Daily Pennsylvanian.. He received a "Men's Senior Honor Award" for "outstanding Service to the University community." He attended New York University School of Law, graduating in 1970. He was admitted to the California Bar, becoming inactive in 2013.

Turtletaub worked for 20 years at The Money Store, a company founded by his father, Alan Turtletaub, in 1967. The Money Store was a pioneer in the subprime lending industry, making home equity secured second mortgage and other loans to people with blemished credit. Turtletaub succeeded his father as CEO and President in 1989, and, took the company public in 1991, then sold it in June 1998 to First Union Bank for $2.1 billion. During his tenure the advertising-driven lending company's growth was phenomenal. At the time of the sale, loan originations were more than $1 billion a quarter, there were 172 branches, and it was the nation's leading home equity lender and Small Business Administration lender. Turtletaub had built a 400,000-square-foot (37,000 m) ziggurat shaped headquarter in West Sacramento, triggering a rebirth in the area. The need for a "deep pocket" had led to the merger; bond rating agencies had downgraded The Money Store to Jun K bond status. Within a day of the merger it had a solid rating. "We will now benefit from the rating of the parent company. We are going to be in the driver's seat," Turtletaub said. The Money Store did not prosper after the merger. At the time of the severe liquidity crisis of August 1998, the subprime industry imploded. Turtletaub resigned as President and CEO May, 1999. By October, 1999, the deal was called a "disaster" for First Union.

With a profit of $700 million from selling The Money Store, Turtletaub decided to go into the film Business. He describes himself as a child of the counter-culture and only wants to make films he is passionate about and that have redemption, something more than entertainment. He wants to touch and change people and use his money, through film, to do good. He looks for movies that have "something that touches my heart," have a powerful voice, and, Illuminate the human condition and emotional connections. He prefers script Writers and Directors who are doing their first films, as he is looking for a fresh perspective. Tutletaub's approach to filmmaking has been described as always "more idealistic than opportunistic." In 2000 he teamed with Producer David Friendly, forming Deep River Productions. The original plan was to use Turtletaub's resources to buy material to develop, then taking the properties to the studios for production. By 2005 he had scaled back, and, moved away from this strategy after an initial spending spree. Several movies were produced by Deep River, most notably Little Miss Sunshine, a 2006 Academy Award nominee for best picture. Turtletaub originally bought the script for $250,000, repurchased it two years later for $400,000 and then paid the $8 million costs of production. The film was a box-office success and critically acclaimed. Friendly and Turtletaub split after a six year run. He joined with Peter Saraf in 2004 to form Big Beach Films, with Turtletaub realizing the "need to specialize." They have produced over 20 movies, and, are best known for lower budget comedy-drama films, such as Little Miss Sunshine and Safety Not Guaranteed. In 2014 they started a TV division, Big Beach TV, which works closely with their L.A. affiliate, Beachside, focusing on micro-budget features and digital content. His theatrical producing debut was in 2009, the Off-Broadway Sleepwalk With Me. In 2014 he co-produced the Broadway revival Of Mice and Men.

Turtletaub has directed two films. In 2011 he directed Gods Behaving Badly, a film adaption of the 2007 satirical novel of the same name. The film was never released, and played only once, at the 2013 Rome Film Festival, where it received negative reviews. He directed the 2018 film Puzzle, an English-language remake of the 2010 Argentinian film, with a planned release of July 13, 2018