The Uruguay international struck for the seventh time in four Ligue 1 games, while Zlatan Ibrahimovic netted two goals and made another for Maxwell with an exquisite chip
The hosts led inside two minutes in the French capital as Cavani angled home his fifth goal in four games.
Ibrahimovic joined him on the scoresheet with a well-taken strike 18 minutes in, with Cavani ending the game as a contest early in the second half.
Talismanic skipper Ibrahimovic turned provider with an impudent chipped assist for Maxwell's header before Cavani sealed his first PSG hat-trick thanks to a quick free-kick from Marco Verratti.
Ibrahimovic converted a late penalty, with Blanc's men needing just four points from their last two games to ensure a third consecutive title.
Serge Aurier came in at right-back - with Gregory van der Wiel and David Luiz both injured - and the full-back supplied the in-form Cavani with the early opener.
The Uruguayan applied the finishing touch to Aurier's delivery as Guingamp were penned back in the opening exchanges.
The visitors eventually tested fit-again goalkeeper Salvatore Sirigu with a long-range free-kick from Claudio Beauvue 12 minutes in.
Sirigu - sidelined with an ankle injury for the last two games - punched the effort clear and it proved a rare period of respite prior to Ibrahimovic doubling the advantage.
Following patient play from Cavani and Verratti, the captain cut back onto his left foot and stroked home his 18th league goal of the season.
Jonas Lossl was required to tip Javier Pastore's close-range effort onto the outside of the post before the half-hour mark although the first period ended scrappily, with both sides regularly committing fouls.
Guingamp made the early running after the break, but were hit by another Cavani sucker punch in the 52nd minute.
The forward doubled his tally as he finished off a slick passing move, latching onto Ibrahimovic's poked throughball to put the game beyond the visitors.
A touch of Ibrahimovic genius allowed Maxwell to bolster PSG's goal difference further with a close-range header before Cavani gained a deserved treble.
With Guingamp switching off, Verratti scooped a set-piece for Cavani to finish before Ibrahimovic completed the rout - scoring from the spot having being hauled down by Jeremy Sorbon.
Blanc's men now have a healthier goal difference than Lyon and are on course for another domestic success, having avenged December's 1-0 defeat in the reverse fixture.