The comedian had been on the panel for 10 years but left the line-up after it emerged that he had made insulting comments about contestants, and former Strictly star Bruno Tonioli is taking his seat at the table.
As filming on the new series got under way, Dixon paid tribute to Walliams by sharing snaps of them on Instagram and writing: “Thank you for 10 amazing years on BGT."
"I love you very much and will miss you dearly,” she added.
The image showed Dixon in a white dress and Walliams in a suit.
Adding a second photo of them, she posted a ring emoji and joked: “Engaged.”
After Walliams' departure it had been rumoured that Tonioli would be joining Dixon, Holden and Cowell on the panel.
The Italian dancer and choreographer had been on Strictly Come Dancing for 18 years but officially bowed out last year.
Earlier this week, the show shared a picture of Tonioli in his new seat on the panel, as he said: "Here we are, Britain’s Got Talent. I am so excited. It’s my first show, I have no idea what’s going to happen, but I’m sure it’s going to be brilliant."
Walliams, 51, found himself in hot water last year when the Guardian reported that he had been overheard making insulting comments about some of those auditioning while on the BGT set.
He apologised, saying in a statement: “I would like to apologise to the people I made disrespectful comments about during breaks in filming for Britain’s Got Talent in 2020.
"These were private conversations and — like most conversations with friends — were never intended to be shared. Nevertheless, I am sorry.”
Watch: Bruno Tonioli has been confirmed as David Walliams’ replacement on Britain’s Got Talent