The former Friends star looked tanned and toned as she walked the blue carpet in Leicester Square, London on Wednesday evening (14 August).
Despite the drizzle in the capital, the 44-year-old looked happy to be in the UK as she beamed for photographers and cosied up to co-star Jason Sudeikis.
Jennifer's cute and flirty dress was a change from her favoured red carpet style of slinky, figure-hugging frocks - and we think she looked amazing!
She jetted into the UK yesterday amid rumours she'd initially been booked on the same flight from Los Angeles to London as Angelina Jolie, although Jen's rep was quick to shoot down claims Jennifer had changed her flight to avoid a run-in.
Jennifer spent her weekend throwing a 43rd birthday party for fiance Justin Theroux at their home in Los Angeles - not, as had been rumoured, getting married!
The actress, who is constantly at the centre of marriage and pregnancy speculation, said on Australian radio earlier this week that no wedding date has been set and any baby rumours are purely because she's put on a few pounds.
We wouldn't have noticed - how incredible did she look in London?!
She plays a stripper in We're The Millers, which is about a small-time pot dealer who ends up creating a fake family in order to carry out a drug deal in Mexico.
It hits cinemas on 23 August.
Watch a trailer for We're The Millers below: