Wild scenes of joy unfolded after the 41-year-old crossed the finish line first in Catalonia. Hamilton last won in Belgium in July 2024, then driving for Mercedes, but has now triumphed for the first time in a Ferrari.
"It felt almost impossible last year, but we never gave up hope," Hamilton said in the victory interview.
George Russell, Mercedes, started from pole position and held the lead until lap 42, when Hamilton made his third pit stop as a virtual safety car slowed the race.
Russell was then challenged by teammate Kimi Antonelli for second place. Antonelli made it past but suffered late car problems and was forced to retire; he had won the last five races.
The 19-year-old Italian still has a clear lead in the overall standings, but Hamilton is making a big push with the victory. Antonelli has 156 points, Hamilton 115.
Hamilton, at 41 years and 158 days old, is the oldest F1 winner since Jack Brabham won in South Africa in 1970.
"I saw Ferrari have a lot of success when I was younger and always wondered what it would be like to win in this car. This is just the first of many, I hope," Hamilton said.
Russell came second and Lando Norris, McLaren, was third on an all-British podium.
