Italian Antonelli, 19, produced a masterclass to become the youngest ever winner of the Monaco Grand Prix, staying ice-cool despite a chaotic ending to the race.
It was a fifth successive victory for the young upstart who replaced Hamilton at Mercedes in 2025 and put him 66 points clear after six rounds of the season.
"He's doing a phenomenal job," Hamilton, who blew a kiss to celebrity girlfriend Kim Kardashian after the race, said.
"He's got an amazing team around him with (Race Engineer) Bono (Peter Bonnington) and (team principal) Toto (Wolff) and the whole team. And then for him in this moment to be delivering on the level that he's delivering, it's awesome to see.
"It just encourages me to want to level up and I think encourages everybody wanting to level up. He's only 19, so just imagine what the future holds for him.
"But I'm going to do my best to try and chase him down for the rest of the year. It's a real privilege to witness it. Very much reminds me of me when I was back in 2007."
Hamilton's second successive runner-up spot, however, suggests that the Briton is beginning to find the old magic after a dismal first season at Ferrari.
His Monaco result put him ahead of Antonelli's teammate George Russell into second place in the standings.
Hamilton had been tipped to end Antonelli's domination and win his first race for Ferrari since joining in 2025. In truth, he was never really able to keep pace with the Italian, although a red flag late in the race did offer him an opportunity to steal the victory.
While a fourth Monaco victory eluded him, the 41-year-old Hamilton equalled the late Ayrton Senna's record of eight podiums in the principality.
"To get another second place is such a great feeling, especially in Monaco, under the trickiest conditions," Hamilton, who was also second to Antonelli in Canada, said.
"Just to be in his presence, in the sense of the eight podiums, is very cool. I still remember being young and watching Ayrton, and still today he's my favourite driver."