An audience of 15.5 million tuned in to watch Manchester United's last-gasp Champions' League triumph over Bayern Munich.
The figures peaked at 18.8 million at 9.30 p.m. - just as Teddy Sheringham and Ole Gunnar Solskjaer scored two injury-time goals to hand their side the treble.
An ITV spokeswoman said: "It was a phenomenal success, by far the highest viewing figures for a sporting event this year. Many people obviously tuned in for the result and they got that tremendous grand finale as well."
But the figures do not match the biggest-ever British audience for a football match - that record still belongs to England's World Cup semi-final last year against Argentina which was seen by 23 million people.