The Sherlock star kept his arm around his pregnant wife while they chatted with the Queen's daughter in the Palace's white drawing room at the Motor Neurone Disease Association (MNDA) reception. The 38-year-old also took time to meet Professor Stephen Hawking, who attended the event with his first wife Jane Hawking.
Ever the dapper gentleman, Benedict wore a blue velvet suit jacket while Sophie showed off her growing baby bump in a blue maxi-dress with an embellished design. It's the first event the two have attended together since the Oscars, where the actor lost out on the Best Actor award to Eddie Redmayne. The pair left for their honeymoon shortly after the award show and returned home to London over the weekend.
As a major supporter of the association, Benedict participated in the ALS Ice Bucket Challenge by having five buckets of ice dumped on him over the summer. But this upcoming summer will be even more exciting as the couple expects their first child together after tying the knot in the Isle of Wight on Valentine's Day.