This is also the third IPL win of the team during the 04 years Mahela Jayawardena joined them as head coach.
Earlier in the evening, Delhi captain Shreyas Iyer won the toss and elected to bat first in favorable conditions.
However, Delhi lost wickets at regular intervals and managed to post only 156 for the loss of seven wickets in their allotted 20 overs.
Skipper Iyer topped scored for the Capitals with an unbeaten 65 off 50.
Rishabh Pant contributed with 56 off just 38 deliveries and the pair put on 96 for the fourth wicket.
For Mumbai, Trent Boult picked up 3 for 30 while Nathan Coulter-Nile had figures of 2 for 29.
Mumbai showed their intent clearly from the outset as they were chasing a record extending their fifth IPL.
Skipper Rohit Sharma and Quinton de Kock raced to 45 in just four overs before the South African was dismissed for 20.
Sharma went on to score 68 off 51 and ensured his side will retain the trophy they won last year at home.
Flamboyant Ishan Kishan played a cameo scoring 33 in just 19 deliveries and helped Mumbai cross the line in 18.4 overs.
Anrich Nortje picked up 2 for 25 for the Capitals but finished second best in the finals.
However, skipper Rohith Sharma not mentioning either the head coach or Trent Boult in his thanking speech after receiving the trophy, has been severely criticized in the field.
Senior commentator and coach Ranjan Paranavithana had posted the following :