Yet Mourinho refused to criticise his side despite another toothless attacking display as they sealed second place in the league with a 0-0 draw at West Ham.
'It feels good, it is my first Golden Glove award, ' he told MUTV after the match at the London Stadium.
Additionally, the Reds' no.1 was voted the Manchester United's Player of the Year by the fans for the fourth time in five years and he also scooped the Players' Player award following another fabulous season between the posts.
A clean sheet in United's 0-0 draw at West Ham United on Thursday saw him claim the Premier League Golden Glove for, astonishingly, the first time in England with 18 clean sheets out of 37 league outings. "Obviously, we are all very happy for David and it is a great team achievement".
It's incredible that it has taken this long for David de Gea to win a Golden Glove Award.
The Spaniard custodian joined the Red Devils in 2011 and has gone on to make over 300 appearances since then, overcoming a hard start to emerge as a worthy replacement to Edwin van der Sar.
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We came second. I am not totally happy (because) that is not my nature but, since the moment we felt it was impossible to finish first, we had the target to finish second and it is done today.
But he admits De Gea's growth has been phenomenal to watch and indicated that his brilliance between the sticks has shielded some shoddy defending from Manchester United.
Considering de Gea is among the best goalkeepers in the world, it's been a surprise to see him win the Golden Glove in his seventh season at Old Trafford.
Eighteen is the highest clean sheet tally recorded in the Premier League since 2012/13, when Manchester City's Joe Hart also kept that amount.
'It is about clean sheets and they are about the team.
Given that it's awards season, we want you to name every single recipient of the honour in just four minutes.