Joe Salisbury claimed the top spot after defeating Feliciano Lopez and Stefanos Tsitsipas in the Miami Open round of 16, alongside American partner Rajeev Ram.
The duo soared up the rankings over the last three seasons, winning both the 2020 Australian Open as well as last year's US Open - taking their title tally to six.
An impressive 2021 saw them win a first Masters title in Canada, as well as finishing runners-up in both the Australian Open and the ATP finals, while Salisbury also won mixed doubles titles at the French Open and the US Open.
After it was confirmed that he'd claim the No.1 crown, Salisbury said, "It seems a bit crazy, to be honest. But yeah, so happy. This week, we're focusing on doing as well as we can, trying to win this tournament in Miami.
"But obviously very satisfied. What we've done as a team, with Rajeev, to be number one in the team rankings as well now, it's pretty special."
The 29-year-old Brit follows in the footsteps of Jamie Murray, who became the first Brit to climb to No.1 in the doubles standings in 2016, while his brother Andy of course rose to No.1 in the singles standings the same year.
As the duo of Salisbury and Rajeev look to add an impressive seventh title to their haul, they'll first have to progress past the tough pairing of John Isner and Hubert Hurkacz in the quarter-finals.
The quartet are scheduled to take to the court on Tuesday, March 29.