Since being called up to the Scotland senior squad over the summer, McKenna has shown significant growth as a player, prompting the club to offer him a new deal.
Speaking about his new contract, McKenna expressed his enthusiasm for the future.
"I'm happy to sign a new deal with the club, which has been great for me since I arrived," McKenna said.
"I feel like I'm improving every day working with the coaches and goalkeepers here. Learning from experienced shot-stoppers like Đorđe Petrovic has helped my game," he added.
"I'm looking forward to seeing what I can achieve in the coming years as I continue to develop," McKenna concluded.
AFC Bournemouth's President of Football Operations, Tiago Pinto, also commented on the new deal.
"We're pleased to see Callan commit his future to the club," Pinto said.
"We believe he has good potential and will continue to work hard to improve his game. We look forward to helping him develop further," Pinto added.
