Kambwala benefitted from injury problems at Man United last season to make 10 appearances in all competitions, including eight outings in the Premier League.
The 19-year-old was expected to again be involved with Erik ten Hag's side during the 2024-25 campaign, but according to the Manchester Evening News, he is now close to leaving Old Trafford.
The report claims that Kambwala is closing in on a permanent switch to Villarreal on a five-year contract.
The teenager allegedly told Ten Hag that he wanted to stay at Man United this summer, but the head coach informed him that he would struggle for action during the 2024-25 season.
Kambwala 'closing in' on switch to Villarreal
According to transfer expert Fabrizio Romano, Villarreal are expected to pay around €10m (£8.4m) for the centre-pack, but there will be a future buy-back clause included in the agreement.
Romano claims that only the 'final details' need to be agreed, and a medical has already been booked in.
Kambwala is believed to have turned down the chance to join Liverpool in order to move to Man United from Sochaux in October 2020, and he made his senior debut for the Red Devils last December.
However, the defender is set to leave the 20-time English champions having featured on 10 occasions.
Man United are not believed to have been planning to sell Kambwala this summer but have been unable to turn down what is considered to be a generous offer from the Yellow Submarine.
Are De Ligt, Yoro and Branthwaite joining Man United?
The Red Devils are said to be closing in on a deal for Matthijs de Ligt, with the centre-back set to join the club from Bayern Munich in the near future.
Man United have also had an offer accepted for Lille centre-back Leny Yoro, but the youngster could yet reject the English outfit in hope of moving to Real Madrid.
The club are also still keen on Everton's Jarrad Branthwaite and could soon make a third offer for the Englishman, having seen their opening two bids turned down.
Raphael Varane has already left the club this summer, while Victor Lindelof and Harry Maguire are being linked with exits, but it was announced on Friday that Jonny Evans had signed a new one-year contract.