Fox is the most experienced of the quintet, having played 24 matches over the past three years, including 11 games this past season.
McLean made his debut in Round 18 this season, and played three senior matches this year.
Bell played two games late this season, while Amartey and Knoll are still waiting for their senior debuts.
Knoll was picked up in the mid-season draft, being selected from the SANFL.
“We’re delighted that Robbie, Hayden, James, Joel and Michael will continue their careers with the Swans for at least another year,” Sydney’s Head of Football Charlie Gardiner told the club’s website.
“Robbie has demonstrated an ability to play a number of roles at senior level and we expect James, Michael, Joel and Hayden to continue to develop and push for more senior opportunities next year.
“They’re all young, exciting, eager to learn and have bright futures ahead of them which is a great result for our football club.”