The interim Ukip leader, who has been informally advising Mr Trump ahead of the November 8 election, attended the televised debate in St Louis, Missouri.
Mr Farage told Sky News: “I thought he was like a big silverback gorilla prowling the studio.
“I don’t think he did it in a particularly aggressive way. I think what you saw tonight is the way he is.
“He took control. He dominated Hillary Clinton. She was very much on the back foot all evening.
“He came into this debate absolutely needing a good performance after a horrendous 48 hours and an embarrassing, cringe-makingly embarrassing 48 hours.
“It was real backs to the wall stuff. He’s come out of this very well. He’ll be leaving here a happy man tonight.”
Mr Farage said he believed Mr Trump could still win the election but admitted it was “awkward” to watch the first part of the debate, which was dominated by discussion about Mr Trump’s lewd comments about women and the Republican’s claim that Bill Clinton was “abusive to women”.
Mr Farage said: “Once we got through that excruciating first 15 minutes - almost a race to the bottom in terms of the way the debate was going - then when we got on to security, dealing with terrorism, business, things like that, suddenly he was winning and winning quite big.
“I don’t suppose there has ever been a presidential debate that plumb the depths that this did in the first 15 minutes but it’s been a pretty extraordinary series of revelations that have come out against both of the candidates frankly.
“I must admit I sort of thought, ‘This is quite awkward to watch. It’s so bad it’s awkward to watch’. But once it was out of the way, it was a very good television spectacle.”