Manager Nigel Adkins said an investigation into Boruc had been concluded after it was alleged he tossed the bottle into the stands during the first half of Tottenham Hotspur's 2-1 win on October 28.
The Poland international can now play in Saturday's match against Swansea City.
"We've had a thorough investigation into the situation against Tottenham," Adkins said on the club website.
"I didn't select him for the West Bromwich Albion game, but the investigation has now been concluded to the satisfaction of the football club.
"Artur is now back in contention for the remaining fixtures."
Southampton are bottom of the Premier League with four points from their opening 10 matches.