Billy Knott got the Wanderers off to the best possible start in the eighth minute, and in some style, when he fired Bloomfield’s cut back into the top corner from the edge of the area.
Scorer turned provider in the 26th minute when Knott’s clever dummy allowed the ball to run through to Bloomfield, who drilled home left-footed.
City reduced the deficit 11 minutes after the break through Brendan Moloney’s long-range strike, but Wycombe comfortably saw out time to secure their passage into the next round.
Gareth Ainsworth made four changes as Nick Arnold, Anthony Stewart, Bloomfield and Josh Scowen came in for Marvin McCoy, Charles Dunne, Gary Doherty and Matt McClure.
Blues started brightly with Paris Cowan-Hall firing over from 20 yards before Sam Wood saw a shot well blocked.
And Chairboys’ dominance was rewarded in the eighth minute when Matt Bloomfield latched on to a pass on the left before cutting back for Knott to rifle home past former Wanderers loanee Frank Fielding and into the top corner from just inside the area.
It was fine strike from the Sunderland loanee and no more than Ainsworth’s men deserved for a bright opening spell.
Kortney Hause and Jo Kuffour then both tried their luck with City struggling to cope with the Wanderers’ attacking play, before Knott was afforded too much space from Cowan-Hall’s lay-off but fired over Fielding’s crossbar.
It wasn’t all one-way traffic though, and Stewart made a fine challenge to prevent Marlon Harewood from breaking through on goal in the 18th minute.
Fielding made a fine save to prevent Stewart from doubling the advantage in the 23rd minute after Knott’s low cross found the centre-back in the area. It was another incisive break from Wycombe, which started with Scowen’s inch-perfect slide-rule pass that found Knott on the right.
Scott Wagstaff saw a low strike deflect wide, but it was the Wanderers who were looking the more threatening and they did add a second three minutes later.
Another free-flowing move saw Knott backheel the ball into Bloomfield’s path in the area and the midfielder switched the ball on to his left foot before drilling low into the bottom corner. After missing so much of last season through injury, Bloomfield’s emotional celebration said it all as he wheeled away before sinking to his knees.
It was so close to being three on the half-hour as Scowen’s ambitious 25-yard drive flew inches wide of the post with Fielding well beaten. Kuffour then fired over the bar after more fine link-up play, this time involving Arnold and Knott, who dummied the ball into the striker’s path.
Blues were enjoying themselves and Kuffour came close to curling in at the far post from the edge of the area after Cowan-Hall’s persistence saw him dispossess a City defender.
Joe Bryan called Matt Ingram into action for the first time two minutes before the break, but Blues’ No.1 was equal to his strike and tipped away for a corner.
Fielding then came to the Robins’ rescue in first-half injury-time when he parried away Cowan-Hall’s powerful shot after the winger had again worked space for himself.
City boss Sean O’Driscoll made two changes at the break, introducing Sam Baldock and Bobby Reid for Joe Bryan and Joe Morrell and they were quick out of the traps with Hause having to hook Reid’s cross over his own bar.
The Robins reduced the deficit in the 56th minute when Moloney broke forward from just inside the Wycombe half before thumping an unstoppable left-footed strike past Ingram from 20 yards.
Ainsworth made his first substitution 20 minutes from time with Max Kretzschmar replacing Bloomfield, who left the pitch to a great reception.
Kretzschmar was instantly involved and tested Fielding from 25 yards, but the shot was straight at Fielding.
The visitors pushed forward, but Blues looked a threat on the break and Cowan-Hall again tormented the City defence before finding Nick Arnold, however, the right-back’s effort was comfortable for City’s keeper.
Matt Spring came on for Knott with 10 minutes left on the clock and Ainsworth made his final change three minutes from time when Arnold, who had been suffering with cramp, was replaced by McCoy.
Wanderers weren’t fully tested in the final few minutes and comfortably held on to secure a deserved win.
Wanderers: Ingram, Arnold (McCoy 87), Wood, Hause, Stewart, Bloomfield (Kretzschmar 70), Lewis (c), Scowen, Cowan-Hall, Knott (Spring 80), Kuffour.
Subs: Horlock, Morias.
Bristol City: Fielding, Moloney, Cunningham, Flint, Dunk, Wagstaff, Pack (c), Morrell (Reid 46), Bryan (Baldock 46), McLaughlin, Harewood (Emmanuel-Thomas 68).
Subs: Parish, Brundle.
Attendance: 1,279 (349 City)