Declan Donnelly joked he had "twice the amount of work to do" as he presented Saturday Night Takeaway without Ant for the first time.
The decision to host alone was made after Ant McPartlin was charged with drink driving following a collision in south-west London.
Ant still had some screen time in a pre-recorded comedy sketch.
Show regulars Scarlett Moffatt and Stephen Mulhern also took on greater presenting roles.
Coming down the steps to loud applause, Dec thanked the audience for the "very, very warm welcome".
"I've got twice the amount of work to do so we're going to crack on," he joked.
Guest announcer and comedian Stephen Merchant told Dec: "I can't help but notice a little bit of space on the stage there - any chance I can come down?"
But he added: "You don't want me standing next to you because I'm 6ft 7in and you're considerably smaller."
The pre-recorded Saturday Knight Takeaway sketch segment - featuring Ant with Dec, Joanna Lumley, Emilia Fox and Michael Sheen - was shown.
After the sketch was played, referring to Ant, Merchant joked: "That other bloke was good - you should do more stuff with him, he was good."
Review: Dec clearly can do it on his own
By Ben Sutherland, BBC News
Could Dec cope without Ant? The answer was - yes, generally very well.
There's no denying that he was nervous to begin with - the tension visible in his body language; his speech was that slight bit quicker than usual.
But he was welcomed to the stage with a massive roar from the audience, and having got into the groove with the usual catchphrases, he nodded to Ant's absence, noting: "I've got twice the amount of work to do."
And the nerves were understandable.
He had no more idea than anyone else how Ant's future might pan out - and he could hardly afford for the general impression to be that he is useless without his partner. At the very least, he isn't.
Merchant later added: "I don't care what the producers are saying back here, I think you're doing a great job."
Moffatt and Mulhern handed out prizes to audience members, a role previously filled by Ant.
During the "Win the Ads" segment, Dec asked the contestant: "Have you been keeping a close eye on this week's news?
When she replied no, Dec said: "For some of us it's been unavoidable."
The presenter finished the show saying "Thanks for all the support", and was seen hugging Moffatt and Mulhern.
Fans, including a number of celebrities, tweeted their support for Dec during the show.
Absolutely brilliant @itvtakeaway Dec was amazing. True proffessional. 💛 laughed and welled up the whole way through. 😂😭🙌🏼— Stacey Solomon (@StaceySolomon) March 31, 2018
Dec, you are just brilliant ❤️ #SaturdayNightTakeaway— Jennie McAlpine (@jenniemcalpine) March 31, 2018
Earlier, the programme tweeted a picture of the front page of the script which read: "Hosted by Declan Donnelly".
It was confirmed in a tweet last week from Ant and Dec's official account that Saturday's episode and the Florida finale would both be hosted by Dec on his own.