The duo have been on loan in north London this term and have certainly impressed head coach Antonio Conte as he looks to rebuild the Spurs team in his image.
According to Fabrizio Romano, the Premier League club will invest around £67million [€80m] for the two players.
Conte's side already have one foot in next season's Champions League following Arsenal's 2-0 defeat to Newcastle on Tuesday night, a result that means it would take a mammoth slip-up from the Lilywhites to miss out at this stage.
While Harry Kane and Heung-min Son claims most of the plaudits, Kulusevski and Romero have also certainly impressed with Conte said to be 'very happy' with the duo.
Kulusevski has particularly shone, with the 22-year-old quickly becoming a fan favourite and even having a new song penned for him by creative supporters.
Since arriving on loan from Juventus in January, Kulusevski has certainly been effective in attacking areas with an impressive record of three goals and eight assists in 19 appearances so far.
He's proven himself as the club's undisputed third attacker in that time too, alongside Kane and Son.
As for Romero, he's the defender that many would suggest Tottenham been crying out for for some time.
Despite enduring a frustrating first half of the season through injury, the Argentina international has made 30 appearances for the club and has proven himself as Conte's most reliable defensive asset since arriving on loan from Atalanta last summer.
Romero even attracted praise from Jamie Carragher on Monday Night Football, with the Liverpool legend describing him as 'a real player'.
He said: "I really like him. Maybe with Romero being my position, I remember watching him at Man City earlier in the season and thinking there is something special about him.
"Every time I watch him play, he takes the ball, he is aggressive. He reminds me of Ricardo Carvalho at Chelsea.
"He isn't the biggest of defenders, but he is clever, he's switched on, he is cool on the ball. I think Tottenham have a real player there."