Campbell has shown promising glimpses throughout his rookie campaign with the Bloods, playing eight games across multiple lines for senior coach John Longmire.
“We have a strong young group of talent coming through at the Swans, and Braeden Campbell is a key part of that. At just 19 he has shown plenty of promise and we are excited to continue working with him to further develop his skillset at the Swans," Swans football boss Charlie Gardiner said on the announcement.
Out-of-contract pair O'Riordan and Sinclair have signed on for the 2022 season with new one-year deals.
O'Riordan has played 29 games for the Swans since making his debut in 2018, featuring in Longmire's side on six occasions in 2021, including one appearance as an unused medical sub.
"O’Riordan is a valued presence both on and off the field at the club," Gardiner added.
"Despite battling injury this year his character never wavered as an exceptional person and valued teammate, and this was evident when he was awarded the 2021 Barry Round Best Clubman. We look forward to seeing what the Irish defender can do in 2022."
Sinclair added a further four AFL matches to his career tally this season, taking his total to 118 games across stints with the Eagles and Swans.
The 2022 season will be Sinclair's 10th in the AFL and seventh with the Swans after moving from West Coast at the end of the 2015 season.
"Callum Sinclair has been a key member of the Swans for a number of years and we are pleased to see him remain at the club for another season," Gardiner said.
"Callum played several senior games this year, while also using his experience to lead our young VFL side during another challenging season.”
Joel Amartey (2023), Nick Blakey (2024), Robbie Fox (2022), Will Gould (2022), Josh P. Kennedy (2022), Tom McCartin (2023), Hayden McLean (2023), Luke Parker (2025), James Rowbottom (2024), Marc Sheather (2023), Dylan Stephens (2023) and Chad Warner (2023) have also re-signed with the Swans in 2021.