World No 1 Selby fended off a charge from Ronnie O'Sullivan to win 10-7 at the York Barbican - his second UK title after first winning the trophy in 2012.
The 33-year-old from Leicester became the sixth player in the sport's history to secure the World Championship and UK titles in the same calendar year.
He joins illustrious company there in O'Sullivan, Stephen Hendry, Steve Davis, John Parrott and John Higgins, and as champion collects £170,000.
Selby promised to celebrate long into the night.
"I'm having flashbacks to 2012," Selby said. "I strolled out of the after-party at 7.30 in the morning, went back to the hotel and went and had breakfast with nine or 10 other families, then went back to the room to get two hours' sleep.
"I woke up at 10 o'clock and thought 'I'll go down for some breakfast', and the woman in the dining room told me I'd already been down and I didn't believe her. It may be similar tonight."
Selby had led 7-2, before O'Sullivan clawed it back to 8-7, before successive centuries from Selby clinched victory.
Selby added: "He put me under pressure, asked the questions and I was really pleased with how I held up at the end.
"I tried to stay in the moment, not get too far ahead of myself."
"To win the three majors is a great feeling but to do it twice is even better. If I never won another tournament I'd be happy with my achievements."
O'Sullivan said: "It's a fantastic night for him.
"I scored all right but I missed too many easy balls.
"I think I did all right considering he's world number one and so far ahead of everyone else."