Mercedes' seven-times Formula One world champion was overcome by the emotion as he took the chequered flag in triumph for the first time since Saudi Arabia on Dec. 5, 2021 - 56 races ago.
Red Bull's triple world champion Max Verstappen finished 1.465 seconds behind, extending his overall lead to 84 points, and McLaren's Lando Norris was third after being passed four laps from the end.
Mercedes' pole-sitter George Russell, winner of the previous race in Austria, retired with a suspected water system issue at the end of lap 33.
"Get in there Lewis, you are the man. You are the man. Mate, I have been waiting for this," yelled Hamilton's race engineer Peter Bonnington, who joined the driver on the podium where he was drenched in champagne, over the team radio.
"Thank you so much guys," sobbed Hamilton in reply, his voice faltering as he choked back the flow of tears inside the helmet while the grandstands --- and a crowd of 164,000 -- erupted on a cold afternoon punctuated by showers.
"It means a lot. Big thank you to all the fans here."
The record-extending 104th win of Hamilton's career set new benchmarks - not least the first F1 driver to win a race in 16 different seasons and first to win nine times at the same circuit.
Hamilton had previously shared the latter record with Ferrari great Michael Schumacher.
He is also the first driver to win a race after reaching the rare milestone of 300 starts. Sunday's was the 344th race of Hamilton's F1 career that started with McLaren in 2007.
"I'm still crying," the Briton told 2009 champion and compatriot Jenson Button, doing the pre-podium interviews, with the flag draped around his shoulders after stepping out of the car and hugging his father in a tight embrace.
"This is my last race here with this team so I wanted to win this so much for them because I love them and I appreciate them so much and all the hard work they’ve been putting in over the years," added the Ferrari-bound driver.
McLaren's Oscar Piastri finished fourth with Ferrari's Carlos Sainz fifth.
Nico Hulkenberg was sixth for Haas with the Aston Martins of Lance Stroll and Fernando Alonso eighth. Alex Albon took two points for Williams and Yuki Tsunoda was 10th for the Red Bull-owned RB team.
Red Bull are now on 373 points to Ferrari's 302 and McLaren's 295, with Mercedes on 221.
'LEAVE ME TO IT'
The race started with Russell leading a Mercedes one-two while Verstappen got ahead of Norris, squeezed into the first corner, for third place from fourth on the grid.
Norris took the place back at Stowe on lap 15 while Piastri also got ahead of the Red Bull two laps later.
Hamilton took the lead on lap 18 of 52, using the drag reduction (DRS) advantage, but both then slid off track and Norris hit the front on lap 20 while Piastri followed him through to slot into second.
The rain then came just before the halfway distance, with Verstappen's Mexican off-form teammate Sergio Perez lapped after starting from the pitlane, and Verstappen pitted for intermediates on lap 27.
The other frontrunners followed, Norris before Piastri who led for a lap but lost precious seconds in staying out, and the order continued until the rain eased and drivers made the switch to slicks.
Hamilton pitted for softs and Verstappen for hards on lap 38 while Norris stayed out in another questionable call and then suffered a slow stop a lap later, coming back out behind the Mercedes.
"Leave me to it, mate," Hamilton told Bonnington over the radio, with Verstappen facing a gap of 3.3 seconds to close in the last four laps.
They were separated by 2.5 at the start of the final lap.
"You couldn't have written it better for our farewell at the British Grand Prix. That was great," said Mercedes team boss Toto Wolff of Hamilton's final home appearance for the team he won six of his titles with.
"He had some difficult times recently. Then, some faultless driving in various conditions.
"The last British Grand Prix together. It's like a fairytale, how we leave the British crowds there with the most successful British driver ever."
