Substitute Erik Nevland grabbed a late clincher and now a win on the final day at Fratton Park against FA Cup finalists Portsmouth will guarantee the most unlikely of escapes, while Birmingham now looked doom.
Galvanised by their astonishing comeback against Manchester City last week, Fulham started positively and would have been rewarded for their bright start were it not for the reflexes of Maik Taylor.
Jimmy Bullard's astute free-kick located the onrushing Simon Davies and his low shot seemed destined for the bottom corner, only for the unsighted Taylor to produce a gravity defying save low to his left.
Birmingham's unwillingness to attack a side who had conceded 31 goals at home prior to kick-off was bizarre and their lack of ambition was summed up by the sight of their most creative force, James McFadden, hurling an aimless long throw into Fulham's penalty area midway through the half.
Indeed, it took until five minutes before the break before McFadden was seen in a more conventional attacking position.
Olivier Kapo's long pass set him free down the left and his low centre would have presented Mikael Forssell with a tap-in were it not for Aaron Hughes' timely interception.
At the other end, Radhi Jaidi performed a similar intervention to prevent Diomansy Kamara opening the scoring from point-blank range on the stroke of half-time.
Former Fulham defender Franck Queudrue replaced the injured Liam Ridgewell at half-time and should have been fully aware of McBride's aerial prowess.
But the Frenchman and his colleagues failed to track the American's perfectly timed run as the Fulham captain ghosted in unmarked to plant Bullard's free-kick past the helpless Taylor in the 52nd minute to send Craven Cottage delirious.
Kamara could have doubled the lead moments later when he wriggled away from four challenges, but failed to match his elegant approach play with a wild finish.
Birmingham responded by switching to a more attacking 4-3-3 formation with Mauro Zarate replacing the ineffectual Kapo just shy of the hour mark.
But it was Roy Hodgson's side who continued to carry the greater attacking threat and would have put the game beyond the visitors had Clint Dempsey's header from Davies' driven cross been a fraction lower.
Substitute Nevland ended any lingering doubts about the result when Quedrue misjudged Paul Konchesky's high ball, allowing the Norway forward to run in on goal and bury his shot past Taylor with three minutes remaining.