There was an hour gone of a hard-fought match when the Scotland B midfielder crashed a shot from the edge of the box in off the post to hand the Bairns a valuable win.
The Homecoming Scottish Cup finalists moved one point ahead of St Mirren who lost at Kilmarnock and they face the free-falling Saints at home on Saturday.
Victory for the Bairns would guarantee them safety with a game remaining.
Falkirk posted their intentions by employing a three-man attack with Steve Lovell, back in the side for the first time in two months following a knee injury, flanked by Michael Higdon and Carl Finnigan.
However, there was little positive about the early stages as both sides battled aggressively to gain the ascendancy.
Gradually James McCarthy began to influence the game down the Hamilton left, linking up at separate times with defender Brian Easton and striker Richard Offiong.
But it was less than enthralling fare and the first attempt on goal did not arrive until the 14th minute when Accies defender Mark McLaughlin unconvincingly headed an Easton corner from the right over the bar.
In the 21st minute, following a spell of pressure on the Falkirk goal, Easton drew a fine save from Dani Mallo with a left-footed drive from 20 yards, the Bairns keeper tipping the ball over the bar for a corner which the visitors survived.
Accies had the slight edge with most of their threat emanating from the talented McCarthy and the energetic Easton.
Falkirk, for their part, were dogged but mostly bereft of inspiration, the midfield failing to provide their strikers with anything resembling a chance.
It was turning into a scrappy affair and in the 37th minute Falkirk's veteran defender Steven Pressley was deservedly booked after preventing McCarthy skipping past him down the left-hand side, the Accies youngster requiring some treatment before coming back on.
In the 45th minute, however, Higdon missed a great chance when he headed Finnigan's cross from the right past the post.
Accies were quickly on the front foot after the break, forcing a series of early corners, albeit none of which threatened to break the deadlock.
The Lanarkshire side were dealt a blow in the 54th minute when Offiong limped off to be replaced by Joel Thomas.
Moments later, Accies keeper Tomas Cerny sprang from his line to block Neil McCann, who had raced on to a Higdon header just inside the box.
There were faint and unsuccessful appeals for a penalty from the Bairns fans but that was forgotten about on the hour mark when Falkirk grabbed a valuable goal through Arfield.
After Cerny had blocked a Finnigan shot six yards out, the ball broke to the edge of the box and Arfield curled his shot high past a posse of players and in off the post, sparking wild scenes of celebration among the travelling support behind the goals.
The tempo increased further as Accies battled back and to the dismay of their fans, Thomas headed over from Kenny Deuchar's cross, the former Gretna player on seconds earlier for Paul McGowan.
In the 75th minute, with Falkirk pinned inside their penalty area, McCarthy blazed an angled shot just over the bar.
Accies substitute Stuart Taylor, on for James Gibson, had a decent shot from 30 yards saved by Mallo and then Deuchar headed wide from close range, Lee Bullen nicked the ball away from McCarthy who then headed over from eight yards.
But the visitors held on and need only a win on Saturday to keep them in the SPL next season.