Gwen Stefani, George Clooney and Julia Roberts take on James Corden's Carpool Karaoke

Gwen Stefani, George Clooney and Julia Roberts join James Corden for his Carpool Karaoke. Credit: YouTube

Gwen Stefani was joined by two of Hollywood's biggest stars in the latest episode of James Corden's Carpool Karaoke.

The feature has become a big favourite on the Late Late show, with Corden regularly joined in his car by some of the most famous names in entertainment.

Singer Gwen Stefani took Corden through the lyrics behind Sweet Escape, before explaining - and acting out - emojis.

Yet the surprise guests were revealed once Corden parked his car on the side of the road, after noticing he required two other passengers to use the HOV 4 lane (a lane set aside for vehicles with full occupancy).

He phoned his friend, George Clooney, because he assumed the actor "had nothing better to do." In turn, the Oceans Eleven star then phoned his co-star, Julia Roberts, who took the final seat in the car.

The group sang various hits including Stefani's Hollaback Girl and Queen's We are the Champions.