It is ironic that United came back from 2-0 down against City themselves last weekend to win 3-2 and delay City's party, only to surrender so tamely on home soil.
Mourinho suggested he had already congratulated his rivals in advance.
Guardiola is the first Spanish manager to win the Premier League, while City also tied United's record by winning the competition with five games to spare.
Victory at Wembley reopened City's 16-point lead at the top of table with only one more win required to secure them the trophy.
A serial victor as a manager with Barcelona and Barcelona, Guardiola ended his first year in England at City without silverware - his only failure to win a trophy since his managerial career started back in 2007.
Manchester United looked to be heading for an embarrassing loss to the Citizens after first-half goals from Vincent Kompany and Ilkay Gundogan.
The 47-year-old also took the German title three times with Bayern Munich, but he believes the unique strength in depth and physical demands of the Premier League makes this triumph among his very best.
Rodriguez was charged with using "abusive and/or insulting words which included a reference to ethnic origin and/or colour and/or race" towards Gaetan Bong during a Premier League match in January.
No side has won more Premier League games that they were losing than Manchester United this season (4, level with Arsenal and Bournemouth), with Jose Mourinho's side winning 33 per cent of the games in which they've been behind (4/12).
West Brom now move to within nine points of safety, although they must face Liverpool, Tottenham and fellow relegation battlers Crystal Palace in their final four matches of the campaign.
Prior to the match, Manchester United knew they only needed not to lose to Baggies to prolong Manchester City's chase for the title.
"We must keep the focus, 100 percent".
United have scored a full 30 goals fewer than City this season and Mourinho has not managed to get his side to click, despite being able to bring on further talent such as Marcus Rashford, Jesse Lingard and Anthony Martial.
But by season's end, City's title will be no less satisfactory.