The winger grabbed a brace in a 3-0 win for Arsenal at the Emirates Stadium on Wednesday night.
After opening the scoring in the first half, Saka capitalised on a defensive error from the visitors to double the Gunners' lead after the interval.
He also played a role in his side's third of the evening as they strengthened their grip on a top eight place in the league phase.
Saka's square ball was prodded in by Kai Havertz via a deflection of Thilo Kehrer.
The England international's goals also saw him join Mohamed Salah in an exclusive club of Premier League players.
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He becomes only the second player from the English top flight to reach 20 goal involvements this season.
Saka now has nine goals and 11 assists to his name so far this term.
Meanwhile, Salah has amassed 16 goals and 12 assists himself across all competitions.
It is not the only eye-catching statistic Saka achieved against Monaco, either.
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Only Harry Kane (18) and Vinicius Junior (16) have been involved in more Champions League goals than the 23-year-old since the start of last season.
His two goals against the Ligue 1 side mean he now has eight goals and five assists since the Gunners' return to the competition.
Arsenal's latest win also takes them up to third in the table after six matches.
Barcelona and top of the table Liverpool are the only sides with more points than Mikel Arteta's side.
Just two points from their final two matches next month will guarantee progression to the knockout phase.
However, they remain just a point above the play-off berths ahead of clashes with Dinamo Zagreb and Girona.