The Red Devils reached that landmark with a 0-0 draw at home to West Bromwich Albion on Saturday.
Another frustrating stalemate is not the result Mourinho would have been hoping for at Old Trafford, having already been held on seven previous occasions at the Theatre of Dreams this season.
He will, however, take heart from the fact that United remain difficult to beat and firmly in contention for a top-four finish.
19 - This is now Jose Mourinho's longest unbeaten run in the Premier League since October 2005 with Chelsea (40 games). Solace. pic.twitter.com/seLVLoxfXk— OptaJoe (@OptaJoe) April 1, 2017
The Red Devils remain fifth in the Premier League table, four points behind arch-rivals Manchester City.
They could, however, end the weekend stuck back in the sixth position that they have occupied for so long this season if Arsenal defeat City on Sunday.
For now, though, Mourinho can reflect on an impressive personal record while contemplating how best to approach the challenges to come during a hectic schedule for his side.