The 45-year-old actress will return to television in Dunham's forthcoming remake of the British comedy Camping, according to Entertainment Weekly.
Dunham is developing the series with Girls executive producer Jenni Konner. Garner plays an "obsessively organized" and "aggressively controlling" wife who organizes a camping trip for her husband's 45th birthday.
"[The role is] messy, tough, provocative and really fun," Dunham and Konner said in a joint statement. "We love Jennifer's restraint and comedic timing, and we can't wait for the warmth and intelligence she'll bring to our central character, Kathryn."
The original Camping had a one-season run on Sky Atlantic in 2016. Dunham and Konner's remake will consist of eight episodes and begin production in Los Angeles in the spring, according to The Hollywood Reporter.
Camping will mark Garner's first series regular role since Sydney Bristow on the ABC series Alias, which ended in 2006 after five seasons. Dunham celebrated the actress' involvement in an Instagram post Thursday.
"We got Sydney Bristow, I REPEAT, WE GOT SYDNEY BRISTOW! @acasualromance production!" she wrote.