Quick-fire goals from Colin Nish and Merouane Zemmama were enough to give Hibs the three points but they had goalkeeper Andy McNeil to thank for saving them late on.
Hibs made a blistering start and were two goals up inside five minutes. A poor clearance from Chris Smith fell to Nish and he kept his cool as he lobbed the ball over the goalkeeper from 25 yards.
Before St Mirren had time to recover, Zemmama hit them with a stunning second goal when he unleashed a 30-yard shot which flew over Smith and into the net.
Zemmama almost scored a third shortly afterwards with a free-kick which Smith did well to clutch under his crossbar.
The little Moroccan then carved out a chance for Nish with a superb throughball but Smith was off his line quickly to block.
St Mirren wasted a good chance to pull a goal back ten minutes before the break when David Barron picked out Craig Dargo in the box but he sent his six-yard header wide.
A misplaced header from Martin Canning then invited Andy Dorman to try his luck from distance but his right-foot shot slipped just a foot wide.
There was a let-off for Saints after 57 minutes when Alan Reid headed against his own crossbar when he attempted to clear Zemmama's corner.
A fingertip save from McNeil then denied St Mirrren when it looked as if Barron had scored with a back-post volley.
Hibs were struggling to create anything but Dean Shiels sent a firmly-struck shot straight at Smith in a rare opportunity for the hosts.
McNeil then made an unbelievable save to somehow keep out a close-range header from Will Haining as Saints produced a late surge.
The St Mirren defender was denied by the goalkeeper again shortly afterwards when he touched Haining's volley past his post.
Haining had another effort in the final minute which the goalkeeper again managed to push to the side.