Callaghan was one of six first-round picks from the 2021 National Draft that remain unsigned for next season, with Sam Darcy, Nasiah Wanganeen-Milera, Ben Hobbs, Angus Sheldrick and Kai Lohmann also yet to recommit to their respective clubs.
Callaghan was among a bevy of Giants yet to cement their future for 2024, however that is now changed with the young midfielder re-signing until the end of 2025.
“It was a pretty easy decision to re-sign with the club,” Callaghan said.
“I'm very thankful and grateful for everything they've done for me over the first few years which was a major part of re-signing.
“I just really love the people inside the club, and it definitely feels like home. The people we've got are brilliant and I'm just really excited for what's to come.”
Callaghan joined the Giants as the third overall pick in the 2021 National Draft, falling between father-son pair Nick Daicos and Darcy in the order.
The Mordialloc-Braeside product managed five games in his debut season before battling an injury that curtailed his rookie campaign.
A foot injury hampered Callaghan in 2022, with off-season surgery placing a delay in his plans for this year.
The 192cm midfielder has impressed across the course of the pre-season so far, looking to slot into a midfield role made available following the departures of Tim Taranto, Jacob Hopper and Tanner Bruhn in last year's trade window.