Folan struck just seven minutes from time to earn Hull a win that they deserved for a powerful second-half display.
Albion, who have picked up only two points from their last three games and surrendered the leadership in the process, had found themselves trailing to a classy piece of finishing by Fraizer Campbell in the 29th minute.
Roman Bednar's 15th goal of the season three minutes before half-time looked to have earned Albion a point, but in-form Hull, who have lost just one of their last 13 Championship games - ironically to Albion, were not to be denied.
After a strangely subdued opening, the game exploded into life in spectacular style when Campbell broke the deadlock.
Albion made the mistake of giving Jay-Jay Okocha far too much time on the ball in midfield and the former Nigeria international came up with a defence-splitting pass to pick out Campbell.
There appeared little danger with Campbell some 25 yards from goal but he came up with a sublime piece of finishing to curl home his ninth goal of the season.
The shock of falling behind finally sparked Albion into life and they thought they were back on level terms just two minutes later only for Zoltan Gera to see his header ruled out for offside.
James Morrison and Gera were then denied by goalkeeper Boaz Myhill before Albion's persistence finally paid off.
Kevin Phillips collected a short pass from Gera and chipped a cross into the area that Bednar powered home with a header from six yards.
Despite equalising just three minutes before the break, Albion could not find the same momentum at the start of the second period and had to ride their luck to stay on level terms.
Dean Kiely came racing out of his goal to try and clear the ball in the 54th minute but lost out to Folan who fed the ball into the path of Campbell.
Campbell looked set to help himself to a second goal but his drive was headed off the line by Leon Barnett.
Ian Ashbee was then denied by a smart save from Kiely before Okocha cut the Albion defence apart again in the 64th minute.
Campbell was the recipient again but this time his finishing let him down as he dragged a shot across the face of goal.
It was left to Folan to show him the way to goal as his classy finish earned Hull a fully-deserved win.
Folan showed a great turn of pace on the left wing and cut past Gera before drilling his fifth goal of the season into the bottom corner of the net.
Gera then missed a great chance in stoppage time to save Albion but blazed a cross from Luke Moore over the bar.