A peak audience of 2.32 million watched the Briton's 6-2 semi-final thrashing of 2018 champion Rob Cross at London's Alexandra Palace on Tuesday.
Sky said that was up 165% compared to last year’s semi-final and 106% more than the previous semi-final record set in December 2017.
The record for a final of 1.65 million was set in January 2015 when Gary Anderson beat 16-time world champion Phil Taylor.
Sky said Tuesday's peak viewing was in line with live coverage of Premier League, Carabao Cup finals and Championship play-off peaks.
"The semi-finals (combined) averaged 1.48m on Sky Sports; the highest performance for any PDC World Darts Championship event, including finals," said Sky.
The Times reported Tuesday's viewership had been "comfortably higher" than the number watching West Ham United draw 0-0 with Brighton and Hove Albion live on Sky in the Premier League.
"Last night Littler v Cross smashed the record with 2.32m audience! Bigger than the Ashes, bigger than the Ryder Cup let’s break 3m tonight for the final," said promoter and Professional Darts Corporation chairman Eddie Hearn on X.
