The F1 world champion was in a close fight with Max Verstappen for the lead at Imola as they made their way through the rears on the wet but dry track.
But, as Hamilton dived offline to pass George Russell, he couldn’t slow down enough on the wet track surface and fled through the gravel pit and into the barriers.
The Mercedes driver managed to back down on the track and benefited soon after when a red flag was signaled for the big crash between Russell and Valtteri Bottas.
This allowed the team to completely repair his car and, although he resumed the race in ninth place, he made his way to finish second.
Lewis Hamilton, Mercedes W12, joins after an off
Photo by: Charles Coates / Motorsport Images
Reflecting on his time at Tosa, Hamilton said afterwards: “There was only one dry line. And I guess I was in a bit of a rush to miss everyone.
“I went inside and could see it was wet. I was trying to stop but the thing would not stop and it sent me back.
“I was a little unhappy but I’m really, really thankful that we were able to start over, and getting points for the team is really important today.
A non-score at Imola would have given rival Verstappen a good lead in the world championship, but the bigger picture was not on Hamilton’s mind as he waited during the red flag period.
“I wasn’t thinking about it,” he says. “I was just trying to get over the feeling you get when you make a mistake, and move on and learn from it really quickly.
“You don’t have time to dwell on it, so that’s what I did: get back into the spirit of the race. I wasn’t sure whether or not we could overtake, because again offline it was going to get wet. But we still had some really good, fun battles with all the guys.
Hamilton recovered to take second place from McLaren’s Lando Norris in the finals, and said he was delighted his former team are doing so well.
“First off, congratulations to Max,” Hamilton said. “He did a fantastic job today and a solid job on his part, and also for Lando, what a great job. It’s so great to see McLaren up there.
“For me, it wasn’t the best of days. So the first time I made a mistake in a long time, but I’m thankful that I was able to bring the car home.