The deal will include an option for United to send Reguilon back to Spurs in January once Luke Shaw and Tyrell Malacia have returned from injury.
United have been in the market for a new left back after both Shaw and Malacia were sidelined with fitness issues, leaving the club short of options in that position.
Reguilon had emerged as a top target for United after talks stalled over a potential move for Chelsea’s Marc Cucurella. Chelsea were demanding a £7m loan fee for Cucurella, while the fact he played in the Carabao Cup last night complicated any potential January exit.
United wanted a clause to allow them to terminate the loan in January once Shaw is expected to be fit again. However, Cucurella would not have been able to move to a third club this season.
There are concerns that Shaw could be out for around two months with a muscle problem.
Reguilon joined Spurs from Real Madrid in 2020 and has made 67 appearances across all competitions. The 26-year-old will now undergo a medical before finalizing a season-long loan to United.