Wanderers were second best for large periods and went behind 10 minutes from time when Jake Hyde converted Luke Gambin’s cross at the near post.
Bruno Andrade won the spot-kick with time running out after being brought down by Tom Flanagan, but Graham Stack guessed right and kept it out.
Kick-off was delayed by 15 minutes due to the larger-than-usual crowd making their way into Underhill for the last ever league game at the ground.
Gareth Ainsworth made three changes to the Wanderers side with Michael Harriman replacing Marvin McCoy, Sam Wood in for Dean Morgan who tweaked a hamstring in the warm-up, and Jo Kuffour taking the place of the injured Matt McClure.
Leon Johnson continued alongside Gary Doherty at the heart of the defence and the game was the centre-back’s 150th for the Chairboys.
The hosts, buoyed by the bumper crowd, started well and Jake Hyde, nephew of Wanderers legend Paul, should have opened the scoring in the second minute. Blues failed to clear a corner and the ball was crossed back towards the far post, but Hyde hit his effort into the ground and it drifted narrowly wide.
The Bees had the benefit of the slope in the first half and they continued to exert the pressure with Charles Dunne forced to make a fine late challenge with the hosts threatening to break through.
Matt Ingram parried Keanu Marsh-Browns’ long-range strike away for a corner after the winger had cut in from the right, and the keeper then saved smartly from David Stephens’ header from the resulting corner.
Hyde wasted another glorious opportunity in the 14th minute, stabbing wide at the near post following a low cross from the right, and the livewire striker then saw a flick from a corner eventually kept out on the line by Ingram.
Blues hadn’t got out of first gear and Ingram then saved from Marsh-Brown after Doherty and Harriman had failed to cut out a through ball.
Ainsworth’s men improved as the half wore on, but it was still the hosts that were creating the chances with Ingram yet again denying Hyde, this time keeping out a near-post header from Davids’ corner.
Ingram was called into action again eight minutes before this break and the 19-year-old made his best stop so far, tipping Curtis Weston’s drilled 20-yard effort wide via the aid of the right-hand post.
Matt Spring saw a free-kick blocked late in the first half and that was all the Blues mustered in a disappointing 45 minutes.
The hosts started the second half as they did the first and Davids fired just wide after bursting into the area.
Stuart Lewis fired high over the bar after his initial strike had been blocked, but the Bees were still enjoying the upper hand and Ingram again saved from Hyde.
Johnson had an effort ruled out for a foul after Gary Doherty had headed Spring’s free-kick back across goal as the Blues started seeing more of the ball with Scowen heavily involved.
Ingram produced a fine save to deny substitute Luke Gambin’s cross-shot, before Stephens headed Mark Byrne’s corner over from close-range.
Ainsworth made a double change with 15 minutes remaining with Bruno Andrade and Junior Morias replacing Wood and Kuffour.
However, it was the hosts who took the lead five minutes later when Hyde got in front of his marker to slot home Gambin’s low cross from the left.
Blues were handed a lifeline in injury-time when Andrade dispossessed a defender and burst into the area before being brought down by Tom Flanagan.
Grant stepped up to take the resulting spot-kick, but Graham Stack kept it out with a fine save to his right.
Wanderers: Ingram, Harriman, Dunne, Johnson, Doherty (c), Spring, Lewis, Scowen, Wood (Andrade 75), Grant, Kuffour (Morias 75).
Subs: Harrison, McCoy, Hause, Ainsworth, Morgan.
Barnet: Stack, Yiadom, Stephens, Flanagan, Johnson, Weston, Byrne, Davids (Oster 85), Marsh-Brown (Crawford 78), De Silva (Gambin 61), Hyde.
Subs: Kuipers, Kamdjo, Nurse, Oster, Vose.
Attendance: 6,001 (857)