Forster joined the Cherries in January on a short-term deal after a spell without a club following his departure from Tottenham Hotspur. He came in as cover after second-choice goalkeeper Will Dennis suffered an injury, and played a supporting role behind first choice Dordje Petrović across the second half of the campaign.
He appeared in four Premier League matchday squads as Bournemouth kept six clean sheets in 19 top-flight fixtures, conceding just 19 goals on their way to a sixth-place finish.
Head of Football Operations Tiago Pinto said the club were pleased to retain him.
"His experience and contributions alongside his fellow goalkeepers last season were invaluable," Pinto said. "He is a key part of our dressing room and someone who can help the group throughout 2026/27."
Forster said he was satisfied with how the six months had gone. "I've enjoyed my time here and look forward to seeing what the group can achieve together going forward."
The Hexham-born stopper began his career at Newcastle United before loan spells at Stockport County, Bristol Rovers and Norwich City, where he won League One. He joined Celtic, initially on loan, winning four Scottish Premiership titles and setting a top-flight record of 1,256 consecutive minutes without conceding. Southampton signed him for around £10 million in 2014, and he went on to make over 150 Premier League appearances between the south coast and Tottenham. He also won the FA Cup with Spurs in 2021 and earned six England caps.
Bournemouth qualified for Europe for the first time in their history last season. The challenge of managing a European campaign while maintaining Premier League standards makes depth in every position a priority, and Forster's willingness to operate as a third-choice goalkeeper for a second consecutive year speaks to both his professionalism and his respect for the opportunity the club has offered him.