Fit-again De Bruyne ran City's south coast show as Manuel Pellegrini's men secured their first Premier League win since March 5, keeping them in fourth place.
Fernando, De Bruyne and Sergio Aguero struck to put City 3-0 ahead and end the contest inside 20 minutes, before Aleksandar Kolarov blasted a fourth at the death.
The imperious De Bruyne's willingness to drive beyond Aguero transformed City's recently stilted play, creating vital extra space for both the lone striker and playmaker David Silva.
The 24-year-old Belgium star offered the pivotal contribution in his first outing since suffering a ligament injury in late January.
Pellegrini's side all-but slipped out of the title race with five defeats in 11 matches in all competitions since the February 1 announcement that Pep Guardiola would take over as manager next term.
De Bruyne's absence effectively ran alongside that sluggish run, and there was little coincidence around City's immediate improvement on his return.
City can ill afford to rest their Champions League qualification hopes on winning Europe's elite tournament, in which they face Paris St Germain in the quarter-finals.
So the importance of this resounding victory stretched far beyond purely boosting confidence - City will view their win as the catalyst to sewing up that fourth-place finish, especially with West Ham and Manchester United circling.
Bournemouth fired out of the blocks but that spark quickly fizzled out as five minutes of dominance quickly gave way to a quarter-hour blitz that settled the tie.
Fernando fired home his first goal of the season after Bournemouth failed to clear Jesus Navas' poor corner, as City took the lead after seven minutes.
The visitors quickly doubled their advantage with the best move of the match
Charlie Daniels surrendered possession cheaply, Aguero chipped in to Silva who laid off to De Bruyne, and the Belgium forward swept home on the volley.
After Aguero lofted it to Silva, the next time the ball touched the ground was when it hit the back of the net.
Cue the spring sunshine, cue the exhibition football from City.
De Bruyne fired over from 20 yards when he could so easily have buried a second, but City wasted little time adding their third.
Navas' persistence paid off when he reached an over-hit pass to keep the ball in play and stand up a cross to the far post.
Aguero did the rest, out-muscling and out-jumping the Bournemouth defence to loop a header back across goal and over the bamboozled Artur Boruc.
Fernandinho hit the bar from 20 yards with Boruc beaten again, before Bournemouth finally rallied.
Steve Cook's glancing header forced Willy Caballero into his first meaningful save of the day from Matt Ritchie's teasing cross as the hosts at least fought to make a fist of things.
City took their foot off the gas after the break, doubtless eyeing Wednesday's Champions League last-eight first leg in Paris.
Pellegrini withdrew De Bruyne before the hour, and Silva just after it.
Eunan O'Kane scuffed a shot badly wide when through for Bournemouth, and City wasted several half-chances, before Kolarov fired an unstoppable fourth for the final word.
TWEET OF THE MATCH
"Outstanding comeback performance #Kdb #WrapHimUpInCottonWool #MCFC" - Former City and England winger Trevor Sinclair thinks the return of Kevin De Bruyne could be the difference between now and the end of the season (@trevor8sinclair).
PLAYER RATINGS
Bournemouth
Artur Boruc: 6
Adam Smith: 5
Simon Francis: 5
Steve Cook: 5
Charlie Daniels: 5
Matt Ritchie: 6
Eunan O'Kane: 5
Andrew Surman: 6
Max Gradel: 5
Lewis Grabban: 5
Joshua King: 6
Subs
Marc Pugh (for King, 46): 5
Tommy Elphick (for Smith, 65): 6
Dan Gosling (for Gradel, 83): 5
Manchester City
Willy Caballero: 6
Pablo Zabaleta: 7
Nicolas Otamendi: 6
Eliaquim Mangala: 6
Gael Clichy: 7
Fernandinho: 7
Fernando: 8
Kevin De Bruyne: 9
Jesus Navas: 7
David Silva: 8
Sergio Aguero: 8
Subs
Aleksandar Kolarov (for De Bruyne, 56): 8
Samir Nasri (for Silva, 65): 7
Kelechi Iheanacho (for Aguero, 78): 7
STAR MAN
Kevin De Bruyne: Transformed City's final-third play on his return after ankle ligament trouble
Astute running opened space for Sergio Aguero and David Silva to shine.
MOMENT OF THE MATCH
De Bruyne swept home City's second goal on the volley after Aguero lofted a ball into Silva, and he in turned laid it off to the onrushing Belgium midfielder
De Bruyne eased the ball home to cement City's dominance and underscore his vast influence on Manuel Pellegrini's side.
VIEW FROM THE BENCH
De Bruyne's return allowed City to let Aguero roam, dropping off into the pocket in the confidence that the Belgium midfielder would bomb past him through the middle at every opportunity
With Silva lurking in the pocket too, City suddenly looked to boast widespread threat
Bournemouth's 4-4-1 set-up hardly yielded any dividend in truth, with Grabban and King unable to make their pseudo-partnership click.
MOAN OF THE MATCH
City scored three good-looking goals, but the first two were also courtesy of ugly errors from Bournemouth
First a poor attempt at clearing a corner gifted City the opener, before Charlie Daniels' daydreaming on the ball allowed the visitors to conjure their magical second.
WHO'S NEXT?
Aston Villa v Bournemouth (April 9, Barclays Premier League)
PSG v Man City (April 6, UEFA Champions League)
Source : PA
Source: PA