The MP Motorsport driver lined up fourth, but was promoted to third after poleman Oliver Goethe suffered an issue in his Trident-run car on the formation lap.
He then passed Prema driver Paul Aron to snatch second before the first stoppage.
Once racing resumed, he made it past Caio Collet (Van Amersfoort Racing) for the first time, with the pair trading the lead several times over the coming laps.
Edgar endured three more safety cars and fended off a fierce challenge from Zak O’Sullivan (Prema) to take his maiden win to round off his third season in F3, while O'Sullivan helped the Italian outfit to another teams’ title.
O’Sullivan’s second-place finish also boosts him to finish second in the standings, with Taylor Barnard taking third for Jenzer.
With Goethe having failed to start the race, Collet led from Aron off the line, before a brief touch of the gravel at the second chicane dropped the Estonian to fourth, allowing Edgar into second after a battle with champion Gabriel Bortoleto (Trident).
The first safety car was then deployed after MP Motorsport’s Franco Colapinto came to a stop at Turn 5 having been forced onto the gravel, ending his hopes of finishing second in the standings.
Racing resumed on lap four, with Edgar taking the lead for the first time two laps later as O’Sullivan took third after Bortoleto ran up the Turn 1 escape road, falling to ninth.
The safety car was almost immediately deployed again, after ART’s Gregoire Saucy went off into the gravel at Lesmo 2.
Action restarted on lap nine, with Aron nudged wide by Leonardo Fornaroli (Trident) at Turn 1 and dropping him to 11th, also ending his chances of finishing second in the standings, though he recovered late on to seventh.
Fornaroli received a five-second penalty for the incident.
Source: Autosport