Andre Brown’s second-half penalty saw Southport slip to their second successive defeat.
Brown delivered the game’s decisive moment 11 minutes after half-time after he was judged to have been tripped in the area by Ryan Astles.
It was a contentious decision by referee James Westage, but the Telford striker made the most of it, sliding the spot-kick to the left of goalkeeper Dan Hanford, who was unable to stop the strike despite diving the right way.
Southport had cause to feel hard done by, having controlled the lion’s share of the play but they were unable to translate their possession into anything tangible.
The home team made a quick start, goalkeeper Corey Addi denying Jack Sampson before later saving from David Morgan.
Devarn Green also sent a fierce shot narrowly wide but the Port failed to capitalise on their early dominance.
Telford captain Shane Sutton drew a fine save from goalkeeper Hanford, who tipped over the header, before the visitors struck soon after the re-start.
Having fallen behind, Southport tried to respond but struggled for clear chances. Addi saved from Morgan, who then went closest to an equaliser with a shot which went wide of the far post.