The ceremony, taking place at the Royal Albert Hall, is hosted by Graham Norton and honors last year's top films.
Onlookers gaped at the royal couple, with Kate, 38, looking ultra slim, walking alongside her 37-year-old husband.
As RadarOnline.com recently reported, sources say William is worried about Kate's weight during the royal shakeup.
According to a Radar source, William and Kate are relieved that the Sussexes hightailed it out of England.
“There are no tears for Meghan leaving,” an insider dished to Radar last month.
Radar previously reported that Prince William and his wife were “so happy Meghan has left. They do not like Meghan. They are celebrating for sure.”
The couple were determined to keep their true feelings hidden, the source told Radar, insisting that they would never speak negatively about Harry and his bride.
But Harry and Meghan wife shocked the world by stepping down from their roles as senior members of the royal family and moving to Canada.
Sources say they want to live in Los Angeles this summer as it appears they want to become financially independent by pursuing show business projects.
Harry has already hustled Hollywood voiceover work for his wife!
A video showed Harry and Meghan speaking to Lion King director Jon Favreau about work for the ex-Suits star last year.
Front runners for awards included Todd Phillips' Joker (11 nominations) as well as Martin Scorsese's The Irishman, Quentin Tarantino's Once Upon a Time in Hollywood (10 nominations each), and Sam Mendes' World War One epic 1917.
The nominations were slammed as heavily male-led and all-white and William disliked the lack of diversity.
BAFTA has since promised a "careful and detailed review" of its voting system.
The awards show's leaders asked guests to make "sustainable" choices on the red carpet and encouraged them to re-wear something they already own as opposed to buying something new.
Scroll through Radar's gallery for more!
Kate looked like a toothpick in a long pale dress at the awards show.
Kate The Great
The British public adores William's wife, the mother of three, especially after the Meghan fiasco.
The royal couple usually attends the BAFTAs, and Sunday night was no exception.
Kate wore a dress with sedate short sleeves but that also showed off her very tiny waist and bust.
The heir to the throne and his lady hit the star-studded red carpet on February 2.
Margot Robbie thrilled in a black dress with short lacy sleeves to support her movie about Fox News.
Pretty In Pink
Scarlett Johansson showed off her body in a shiny fitted long dress with an odd feathered bottom.
Actress Laura Dern rocked the red carpet in a sleeveless gown.
Renee Zellweger appeared in a satiny pale pink, off-the-shoulder number.
Charlize Theron flaunted herself in a long purple, low cut, strapless dress with a small black belt accentuating her waist.