The star is seen fighting and making up with his girlfriend in the Bill Condon-directed clip, which was released online this morning.
It was recently reported that the video's premiere had been delayed by two weeks, after Mars tweeted: "Be patient for ya boy. Love y'all."
The track serves as the lead single on the Twilight: Breaking Dawn - Part 1 film soundtrack, and has so far peaked at number 16 on the UK midweek chart and number 12 on the Billboard Hot 100.
The soundtrack, which also features cuts from Christina Perri and The Noisettes, is available to download now.
Watch Mars's 'It Will Rain' video below:
For US users only: