Alan Pardew's side came from a goal down to win their sixth game of the season and they are now just a point from safety, while Pools, reduced to 10 men for the last five minutes after Richie Jones received a second yellow card, took a deserved lead in the 16th minute.
Andy Monkhouse started the move, then got forward to meet a high James Brown cross and head in his fifth of the season. Pools had further chances to double their lead, but were pegged back in the 29th minute.
Two minutes after missing an open goal, Rickie Lambert played Adam Lallana in and he confidently slotted home from 18 yards.
The pair linked up to good affect in the 53rd minute to put the Saints ahead. Lambert's header was laid into the left winger's path and he cut inside to curl a lovely shot over Scott Flinders into the far side of the net.
The Pools goalkeeper was at fault for the killer third, his clearance smashing against Lambert who easily tapped in before Jones was sent-off in the 85th minute following a melee on the touchline involving 18 players.