Sumner has been one of the few Giants to hold off contract negotiations since joining the club as one of its 11 first-round draft picks in 2011.
But AFL.com.au understands the speedy wingman is on the verge of committing to a new contract, likely a three-year term, to extend his stay at the club beyond the end of this season.
The former Sandringham Dragon had Victorian clubs circling given he hadn't joined the likes of Jonathon Patton, Toby Greene and Stephen Coniglio in re-signing with the club.
However their interest is set to be doused just as Sumner, a No.10 draft pick, begins to show his skills at the top level.
Sumner played two games in his debut season of 2012 before being sidelined with a foot injury for the majority of the year.
He has broken into the Giants' side this season, playing all four games so far.
The former AIS-AFL Academy member's pace, quality kicking and tenacity have been clear through the midfield and half-forward.
In the club's round-one loss to the Sydney Swans, the 19-year-old collected 16 disposals and kicked two goals.
Sumner's imminent signature means the spotlight could turn to out-of-contract teammates Taylor Adams and Nick Haynes, with the Victorian pair's respective two-year deals expiring at the end of this season.
The Giants have signed a majority of their list until the end of 2015, including other young stars Dylan Shiel, Devon Smith, Tom Bugg, Jeremy Cameron, Adam Tomlinson, Matt Buntine and Dom Tyson.
Giants co-captain Phil Davis last month said the Giants were able to sign their players because all could sense success wasn't too far away.
"I think the people who are re-signing now, it's about what they think we're going to do. Everyone is pretty confident we're heading in the right direction," Davis told AFL.com.au.
Follow AFL website reporter Callum Twomey on Twitter at @AFL_CalTwomey.
