The show returned on BBC One with a thank you to NHS frontline workers, who were invited to be in the audience at a social distance.
Olympic boxer Nicola Adams and Katya Jones danced the quickstep as part of Strictly’s first same-sex couple.
Judge Motsi Mabuse said she had been intrigued to see what the pair would come up with.
“I have to say I was very curious, ‘How is it all going to happen? How is it going to turn out?’” she said.
“And you haven’t disappointed me… We loved it, keep going.”
Craig Revel Horwood said the dance was “absolute dynamite” while Shirley Ballas said Jones was a “genius” for coming up with the choreography.
“I’m a dancer baby,” Adams exclaimed and the three judges awarded the pair a total of 21 points.
Ex-home secretary Smith is last place on the leaderboard after taking to the dancefloor with Anton Du Beke to perform a foxtrot with top hats.
“This is my chance to show you can have a new adventure even when you’re getting on a bit,” Smith said.
She played on her former career as a politician, with a dance which began with Smith pretending to be a candidate sitting next to a ballot box.
Revel Horwood had plenty of criticisms, but also some good news.
“When you consider Theresa May and her dancing, I think you’re 10 times better than that,” he said.
The pair were awarded 13 points by the judges.
Singer HRVY and Janette Manrara closed the show with a jive and shot straight to the top of the leaderboard, with 25 points.
Mabuse said it “was the best first dance I have ever seen”.
EastEnders actress Maisie Smith and Gorka Marquez impressed judges with a samba, scoring 24 points.
Made In Chelsea star Jamie Laing, who was invited back for a second year after having to leave the last series when he was injured, was the first to dance live on this year’s show.
Revel Horwood called Laing’s performance “flat-footed, very tight and restricted”, and added: “That might have something to do with those lovely trousers you are wearing, don’t leave much to the imagination do they!”
Laing said afterwards he was “nearly physically sick” at the prospect of dancing first, doing the cha cha cha with Karen Hauer.
“I had to go to the bathroom, I thought I was going to throw up, I gagged a little bit but I was fine,” he said.
Actress Caroline Quentin was in tears after performing the American Smooth with her professional partner Johannes Radebe.
Claudia Winkleman and Tess Daly paid tribute to NHS workers before the celebrities took to the dancefloor.
“We have invited some very special people to be in our audience tonight. We are delighted to be joined by some of our incredible frontline NHS workers,” Daly said.
“Thank you so much for everything you have done for us and everything you continue to do and we really hope you enjoy tonight,” Winkleman told the NHS workers, who sat at a distance.
Good Morning Britain presenter Ranvir Singh also impressed the judges, scoring 21 points, with Revel Horwood saying she moved her dress “like her life depended on it.”
The show also saw performances from former marine and TV presenter JJ Chalmers, DJ Clara Amfo, The Wanted singer Max George, Former NFL star Jason Bell and comic Bill Bailey.
Bruno Tonioli made a short appearance on video, from the US, and will return to the show later in the series.
A celebrity will not be voted out until next week.