The Mad Men actor, 44, completed the program just days before the April 6 premiere of the final season of the hit AMC show and after filming had already wrapped.
According to TMZ, Hamm checked himself into and sought treatment at nationally recognized psychiatric Silver Hill Hospital in New Canaan, Connecticut.
"With the support of his longtime partner Jennifer Westfeldt, Jon Hamm recently completed treatment for his struggle with alcohol addiction,” his rep told Us Weekly in a statement. “They have asked for privacy and sensitivity going forward."
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!