He's the latest player to commit to the club in the last six months after the club secured the signatures of Travis Boak, Brad Ebert, Hamish Hartlett, Jay Schulz and Jake Neade before Christmas and Justin Westhoff, Jasper Pittard, Cameron O'Shea and Ollie Wines in March.
Jonas, 23, grew up in Adelaide and attended the highly regarded football school Rostrevor College in the city's foothills.
Tom Jonas profile
Playing for Norwood in the SANFL, he was taken with pick 16 in the 2011 Rookie Draft and was upgraded to the senior list both that year and in 2012 to earn a senior elevation for the 2013 season.
He played 21 games in 2013 including the Power's two finals and has featured as part of the club's defensive backbone in every game of 2014.
Likely to play his milestone 50th game later this year, Jonas told portadelaidefc.com.au it was an easy decision to recommit to the club for a further two years.
"It's great to be on board at the footy club for another two years," Jonas said.
"The group we've got here is really good and I want to be part of it moving forward."
Jonas's story is one of hard work and persistence.
The reward for effort that saw him become a senior-listed player last year is unsurprising given the role Jonas - the 2012 Coaches' Award winner - plays inside the club's walls as well as on the field.
His leadership qualities led to him joining the club's leadership group for 2014 and as a typically hard, gutsy player in the mould of a classic shutdown backman, Jonas looks set to be an important part of the Power's back six for years to come.
He's looking forward to those years, particularly following the excitement of playing at the clubs' new home ground, the Adelaide Oval.
"It's always been about working hard, playing a selfless role for the team and consistently improving and that's the way I've always tried to approach my footy," Jonas said.
"To come off the rookie list and earn a place as a senior player is a rare opportunity and I understand that, so I've always wanted to repay that faith shown in me by the club.
"It's a great place to be and playing at Adelaide Oval has been really special and it's going to be exciting to be part of that in the years to come."
Tom Jonas has played 40 AFL games for Port Adelaide.
