Italian Sinner’s triumph on home soil was the latest moment of glory in a near-perfect year in which the 23-year-old won eight tournaments, including his debut Grand Slam victories at the Australian and US Opens.
World number one Sinner again swept Fritz aside in straight sets just as he did in the group stage and the US Open final in September.
Sinner is the first Italian to win the Finals, doing so days after becoming the first from his nation to top the ATP’s end-of-year rankings.
His Tour-leading 70th win of the season made him the first player since Ivan Lendl in 1986 to win the tournament without dropping a set.
The first set went in Sinner’s favor after an enthralling seventh game which lasted nine minutes and was eventually won on the fourth break point.
And despite Fritz’s best efforts he couldn’t fight back, failing to get a single break point in the second set and succumbing to his opponent’s superiority.
Sinner has reacted to losing last year’s final to Novak Djokovic by displacing the Serbian great at the top of the game.
However, he has been dogged by controversy after twice testing positive for traces of the steroid clostebol in March.
A World Anti-Doping Agency appeal against his initial exoneration has been hanging over his head since September, when WADA announced it was seeking a ban of up to two years.