Kanye West sang a tribute to Caitlyn Jenner.

The 'Bound 2' rapper reportedly performed a rendition of Stevie Wonder's 'Isn't She Lovely' for the 65-year-old former Olympian - who was known as Bruce Jenner before undergoing a gender transition - at her Father's Day celebration on Sunday (21.06.15).

A source shared: ''Out of nowhere, Kanye asked Caitlyn and the others who were there to have a seat because he wanted to say something.

''He said, 'This is for you, Caitlyn,' and he just started belting out the most wonderful rendition of Stevie Wonder's 'Isn't She Lovely.'''

The touching tribute moved Caitlyn, who was left ''in tears''.

The insider added to HollywoodLife.com: ''The whole point was for Kanye to convey to Caitlyn that she's lovely and that everyone in that room, including himself, loves her.

''Caitlyn's mouth dropped and she was in tears. She thought it was beautiful and epic.''

Caitlyn clearly had a great day with her family as she took to Instagram to share a snap of the group's special day.

She captioned the photo: ''Great day yesterday for Father's Day. We had so much fun off-roading. So much love and support! Love my family! (sic)''