The 35-year-old played arguably his best match of the week, as the 21-time Grand Slam champion was rock-solid on serve and impeccable in defence. After squandering break points in the second and eighth games of the first set, he broke Ruud in the 12th to take the opener.
Riding his momentum, the Serb broke Ruud's serve once again to reign supreme at the season-ending event for the sixth time.
With the triumph, Djokovic achieved quite a few landmarks and records. Here's a look at five of them (in no particular order):
#1. Goes level with Roger Federer for most ATP Finals titles
Novak Djokovic produced a near impeccable week in Turin — dropping his lone set of the week against Daniil Medvedev — to win a record-tying sixth ATP Finals title.
With the triumph, Djokovic has now moved level with Roger Federer atop the competition's all-time title leaderboard.
It was Djokovic's fifth title of the year, with each title coming in as many tournament categories (ATP 250 - Tel Aviv, ATP 500 - Astana, Masters 1000 - Rome, Grand Slam - Wimbledon, ATP Finals). He has won titles on all three surfaces this year (hardcourt - 3, clay - 1, grass - 1), winning four of them outdoors and one indoor.
World No. 1 Carlos Alcaraz is the only other player to win five titles this year. The Spaniard was absent at the ATP Finals due to injury.
#2. Novak Djokovic becomes oldest ATP Finals winner
Continuing to age like fine wine, Novak Djokovic provided another demonstration of his pedigree by becoming the oldest player to win the ATP Finals.
After falling short in the 2016 and 2018 finals, Djokovic came good at the third time of asking to win a record-tying sixth title in the competition. In the process, the 35-year-old also became the oldest player to do so, beating Federer's record by more than five years. The recently retired Swiss was 30 when he won his sixth title in 2011.
Djokovic is only the second player over 30 to win the season-ending event, with Federer being the other.
#3. First player to win ATP Finals in three different decades
Novak Djokovic hadn't won the ATP Finals since 2015, when he completed an unprecedented four-peat.
With his first title at the season-ending event in seven years, he has now won the ATP Finals in three different decades, becoming the first player to do so. The Serb's first title in the competition came in Shanghai in 2008, while his next four came in consecutive years in London between 2012 and 2015. Four of those triumphs have come without dropping a match (2012-14, 22).
Moreover, his latest ATP Finals win broke Federer's record of the longest gap (8 years) between wins at the competition by six years. Djokovic's first ATP Finals title came in 2008.
#4. First player to win six titles at six 'big' tournaments
Novak Djokovic is already the all-time 'big' title leader (Masters 1000, ATP Finals, Grand Slam), winning 65 such titles.
With his latest triumph, he has now won at least six titles at six different tournaments — Australian Open (8), Wimbledon (7), ATP Finals (6), Paris-Bercy (6), Miami (6) and Rome (6).
The former World No. 1 is the record title holder at three of those tournaments — Australian Open, Paris Masters and Miami Open.
#5. Novak Djokovic earns biggest paycheque in tennis history
The 2022 ATP Finals offered a record paycheque of $4.74 million to the undefeated champion.
With Djokovic romping to the final without dropping a match all week, he was in line to receive the biggest prize money in tennis history. By beating Ruud in straight sets, he ensured that slice of history as he completed a memorable week in Turin.
Earlier in the week, the World No. 8 had become the first player — male or female — to earn $160 million in career prize money.