Nusa had emerged as a transfer target for Tottenham after a recent report revealed they had opened talks with Club Brugge over a potential move.
Tottenham were believed to be at the front of the queue for Nusa's signature despite Newcastle United showing an interest.
However, it appears that Spurs have lost out to another Premier League club in the race to recruit the Norway international.
According to journalist Fabrizio Romano, Brentford have now reached an agreement with Club Brugge to sign the highly-rated prospect.
The deal is said to be worth around €30m (£25m) and will see Nusa return to the Beglian side for the remainder of the current season.
The Bees will now work on the final details of the transfer, which will include scheduling a medical, before they unveil Nusa as a Brentford player.
Nusa, who has also been linked with Chelsea in the past, has seemingly been impressed by Brentford's plans for his development.
Despite being just 18, Nusa has already made 64 competitive appearances for Club Brugge since arriving from Stabaek of Norway in August 2021.
The winger has featured in 28 matches this season, scoring four goals and providing five assists for Ronny Deila's side.
Having impressed for his club side, Nusa has gone on to earn four international caps for Norway, including a goalscoring debut against Jordan in September.
Brentford will be pleased with their work after they failed in their attempts to sign a number of attacking players in the summer transfer window.
Thomas Frank's side were unsuccessful in their efforts to recruit Nicolas Gonzalez, Brennan Johnson and Johan Bakayoko.
Nusa will become their fourth addition of the January transfer window, following the arrivals of Yunus Emre Konak, Sergio Reguilon and Hakon Valdimarsson.