Weiner served as a supervising producer for the fifth season of The Sopranos (2004), a co-executive producer for the first part of the sixth season (2006), and an executive producer for the second part of the sixth season (2007). He has sole or joint credit for 12 episodes overall, including the Primetime Emmy Award-nominated episodes "Unidentified Black Males" (co-written with Terence Winter) and "Kennedy and Heidi" (co-written with David Chase). He received two Primetime Emmy Awards as a producer of The Sopranos — one for the show's fifth season in 2004 and one for the second part of the show's sixth season in 2007.
In addition to writing and producing, he acted in two episodes, "Two Tonys" and "Stage 5" as fictional mafia expert Manny Safier, author of The Wise Guide to Wise Guys, on TV news broadcasts within the show.
Weiner also spent the hiatus between the two seasons teaching at his alma mater, the University of Southern California School of Cinema-Television (now School of Cinematic Arts), where he taught an undergraduate screenwriting class on Feature Rewriting during the Fall 2004 semester.
After The Sopranos concluded in 2007, Weiner began looking for a network to produce Mad Men. Both HBO and Showtime passed on the project. HBO offered to produce the series if Chase would be on board as a writer or producer, but Chase instead chose to focus on developing feature films. Weiner eventually pitched the series to AMC, which had never produced an original dramatic television series. They picked up the show, ordering a full 13-episode season. Weiner has served as showrunner, an executive producer, and head writer of Mad Men throughout its six seasons, each consisting of 13 episodes. As the showrunner he has had a major role in the writing and directing of each episode, also approving actors, costumes, hairstyles, and props. He is credited with writing or co-writing seven episodes of the first season, eleven episodes of the second, twelve episodes of the third, ten of the fourth, and nine of the fifth. He has also directed all six season finales.
A March 2012 New York Times article by Dave Itzkoff described Weiner's writing process for Mad Men. Weiner said "[t]here's about a three-week rumination period [8 to 12 weeks before shooting begins], which involves a lot of napping, a lot of holding books. Whether I'm reading them or not, I cannot say." Itzkoff writes that Weiner ruminates on his own life during this period and "[talks] with series consultants like Bob Levinson, a veteran ad man of the '60s, and [contemplates] the real-life history that might have an impact" on the series' characters. "Then he gathers his writers, who are each assigned to bring in 10 story ideas; Mr. Weiner acknowledged that he shoots down many of these pitches. From what survives, an outline is generated, a script is assigned, and when it comes in from his writers, Mr. Weiner rewrites it." "If I change less than 80 percent of it, I will leave their name on it by themselves," Weiner said, adding "I would never want my name on something that I did not write most of. Part of television is you get rewritten."
Weiner is married to architect Linda Brettler. Marten, one of his four sons, plays the recurring role of Glen Bishop on Mad Men. Weiner currently resides in Los Angeles. He was a one-day champion on the quiz show Jeopardy!