Photos of the singer sporting the new hairdo while standing next to bandmates Niall Horan and Zayn Malik at BBC studios have been leaked on Twitter ahead of tonight's (March 15) Red Nose Day event.
Tomlinson will debut his red hair when One Direction perform their official Comic Relief single 'One Way or Another (Teenage Kicks)' during the BBC One broadcast, which kicks off at 7pm.
Tomlinson's Red Nose Day look came in response to a Twitter petition from his beloved Doncaster Rovers Football Club, after the whole team donned red lipstick to raise money for Comic Relief.
One Direction also played with this year's dinosaur red noses in behind-the-scenes images from a Comic Relief shoot.
Earlier in the year, the group visited projects in Ghana supported by Comic Relief.
Harry Styles's celebrity pal Nick Grimshaw yesterday dyed his hair pink to celebrate his Radio 1 breakfast show raising £250,000 for Comic Relief, while Jessie J will have her head shaved on tonight's show.