"He has competed his treatment and has left," his rep told the magazine. Arquette, who left the facility Sunday, originally entered to seek help for "alcohol and other issues" nearly a month ago.
"He's feeling good and he's ready to move forward," a source told the magazine.
In October, Arquette, 39, and Courteney Cox, 46, announced their separation after 11 years of marriage. "I really admire David and his choice to take charge and better his life," Cox said when Arquette entered rehab. " I love and support him." The couple has a 6-year-old daughter.