The 2007-born attacker was previously on the books at Arsenal, where he developed into one of the most lethal young attackers in the land and made frequent headlines with his goalscoring exploits.
Obi Martin achieved international fame when he scored 10 goals in an Under-16s match against Liverpool, and he netted an astounding 32 goals in just 18 games in last season's Under-18s Premier League.
The 16-year-old cannot sign a professional contract with a Premier League club until he turns 17 in November, although Arsenal fought tooth and nail to tie him down to scholarship terms after his rise to prominence.
Such a renewal would have preceded a professional contract signing as soon as he was eligible, but despite Arsenal tabling what they believed was a fair offer, Obi Martin decided that his future lies elsewhere.
Obi Martin 'rejects' higher offers to join Man United
The Denmark youth international confirmed on Instagram on Tuesday that he had left Arsenal, and for the past couple of weeks, Man United have been working to bring him to Old Trafford.
According to Fabrizio Romano, that switch is now on the verge of completion, as Obi Martin has given the green light to Man United's contract proposal after being 'convinced' by the Red Devils' project.
The youngster reportedly rejected higher bids from Bundesliga sides - thought to be Borussia Dortmund and Bayern Munich - to link up with Erik ten Hag's side, as he believes that his pathway to the first team will be the clearest in Manchester.
The 2023-24 campaign saw one Carrington academy product in Kobbie Mainoo excel on the big stage, earning him a spot in England's Euro 2024 squad, while Alejandro Garnacho has also been promoted from the youth ranks.
Obi Martin would likely start out in the Man United Under-18 or Under-21 team and work his way up to senior level, but it would not be a surprise to see him train with the first team straight away.
Deja vu for Arsenal as Obi Martin edges closer to Man United
This one will hurt for Gooners, for more than one reason. From Robin van Persie in 2012 to Alexis Sanchez in 2018, this is not their first rodeo when it comes to losing exceptional attacking talents to the Red Devils.
Of course, Sanchez did not achieve anywhere near the same level of success at Old Trafford as Van Persie did, but with Obi Martin opting for project over pounds and seemingly being promised a route into the first team, the 16-year-old can be expected to follow in the Dutchman's Mancunian footsteps rather than the South American's.
Some home-grown exits will be welcomed by the powers-that-be at Arsenal this summer - Emile Smith Rowe, Reiss Nelson and Eddie Nketiah for example - but they are fighting losing battles to retain the new crop of Hale End stars.
Before negotiations with Obi Martin broke down, Reuell Walters and Amario Cozier-Duberry also turned down the chance to sign new deals; they are now at Luton Town and Brighton & Hove Albion respectively.
Of course, the likes of Smith Rowe, Nketiah and Bukayo Saka came through the ranks when Arsenal were nowhere near challenging for the Premier League title, but while the standards for youth players may now be significantly higher, a continued lack of competitive exposure will see this worrying trend of exits continue for Mikel Arteta.