The 19-year-old netted twice in West London, getting Man United back into the game after going 2-0 down early on, before putting the Red Devils in front midway through the second half.
Erik ten Hag's side would still go on to lose the game though, with Cole Palmer striking twice after the 100th minute to hand Chelsea a late victory.
On a personal note though, Garnacho has set a goalscoring feat not seen in the Premier League for 25 years thanks to his brace tonight.
Garnacho equals Michael Owen's record in Chelsea clashFor the first time since the 1998-99 season, a teenager has scored three braces in a Premier League campaign, following Garnacho's double tonight.
The young Argentine also managed to net twice in a 3-0 win over West Ham United back in February amidst a five-game winning run for the Red Devils.
It was Garnacho that was instrumental in a comeback win over Aston Villa on Boxing Day as well, getting the two goals that pulled them level after going 2-0 down, before Rasmus Hojlund fired home the winner.
That means Garnacho has become the first teenager since Michael Owen to achieve such a feat after he did so in the 98-99 campaign, in a season where the former Liverpool and Man United striker managed 23 goals.
Garnacho enjoying productive season despite United's strugglesAs mentioned earlier, Garnacho has played a huge role in some of United's better results in what has been, overall, a disappointing campaign so far.
The winger is now one shy of hitting double figures for goals in what is just his second senior season in the United team.
Only
Read on sportsmole.co.uk