Hereford ended their dismal run of three straight Nationwide Conference defeats on Tuesday but it took a 90th-minute header from club captain Ian Wright at Haig Avenue.
The result also maintained United's unbeaten record against the Sandgrounders since relegation to the Conference, although six of those eight matches have ended in draws.
Home midfielder Neil Grayston looked to have given fourth-placed Southport victory with his first goal of the season in the 63rd minute of an entertaining match.
But in the closing seconds of stoppage time central defender Wright headed home after the Southport defence failed to clear a corner from Paul Parry, which gave Hereford a point and lifted them to ninth in the table.
Bulls chief Graham Turner rested several players ahead of Saturday's vital FA Umbro Trophy match at Forest Green and handed keeper Matt Baker his first start for the club.
Regular stopper Scott Cooksey, who was not chanced due to a slight wrist injury, was on the bench - the first time he has failed to start since his arrival at Edgar Street - along with striker Rob Elmes.
Former Hereford right-back Chris Lane, who was transferred to Haig Avenue earlier this season, started for Southport, who were forced into two half-time changes following injuries to defender Scott Guyett and front man Simon Parke.
The encounter remained goalless until Ian Arnold caught out the Bulls defence with a run down the right.
From his centre, Grayston beat Baker with a 20-yard shot, which appeared sufficient to hand Southport a narrow win until Wright's last-gasp equaliser.
Southport manager Mark Wright was philosophical after the game and said: "Scoring has been our problem all season and we squandered enough chances to have won.
"But Hereford are a good side and overall they deserved at least a draw."
Southport: Dickinson, Linighan, Guyett (Teale 46 mins), Clark, Lane, Marsh, Grayston, Stuart, Arnold (Elam 70 mins), Parke (Furlong 46 mins), Maamria. Subs not used: MacAuley, Whittaker.
Hereford: Baker, Clarke, Wright, James, Shirley, Quiggin, Crowe, Snape, Rodgerson (Hanson 78 mins), Giddings (Bull 78 mins), Parry. Subs not used: Elmes, Cooksey, Wall.
Referee: W Oliver.
Attendance: 1,367.
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