The actress's rep tells PEOPLE the reports that she and Affleck, 41, are expecting their fourth child are simply "not true."
Recent photos of Garner, 42, sporting loose-fitting tops while out and about in L.A., promoted the speculation.
Affleck meanwhile has been busy shooting the new Batman v Superman film in Detroit.
The couple are parents to children Violet, 8½, Seraphina, 5, and Samuel, 2.
The film stars, who wed on a beach in June 2005 after dating for 10 months, have been fiercely devoted to their family.
"She is by leaps and bounds the most important person to me in that respect," Affleck told Playboy of Garner's resolute support. "Over the past 10 years she has allowed me to have a stable home life while accomplishing my professional goals."
Reporting by JULIE JORDAN