Hosking is already 25 and the Manly-born edge forward impressed during his four NRL games for the Red Hill-based club at the back end of 2022.
The second rower will be fighting for minutes almost immediately at Penrith given their off-season departures includes edge forward Viliame Kikau, which follows last year's departure of Kurt Capewell.
Cogger is the far more surprising signing for Penrith.
A halfback and five-eighth, the 25-year-old debuted as a talented prospect at the Newcastle Knights in 2016, however, played just 20 games for the club before switching to the Canterbury Bulldogs in 2019.
“On behalf of all at Panthers, we look forward to welcoming Zac and Jack to the club ahead of the new season,” Panthers Rugby League CEO Matt Cameron said in a club statement.
“Jack joins the club with NRL experience and will add depth to the Panthers top 30 squad. The opportunity Jack has to work alongside representative halves Nathan Cleary and Jarome Luai will also be beneficial to his game.
“Zac's experience and capabilities make him an excellent addition to our squad and we're delighted to welcome him on board. We believe Zac will really flourish in Panthers colours.”