A Charlie Romain strike proved to be the difference as the Barrowmen claimed the three points and make it their first win in 11 league games.
The game kicked to life early on – after just seven minutes Romain rifled home into the roof of the net after the Tigers back line failed to deal with a Grant Radmore cross.
The Barrowmen had a number of opportunities to double the lead as Matt Hards twice came close.
Matt Hurley then had a header cleared off the line by the hosts as they looked to hold on.
Jared Rance came close for Saltdean after some superb interplay but could only see his effort go wide of the goal
The hosts had a shout for a penalty soon after but was waved away by the referee.
Rob Clark was next to test the Saltdean keeper with a stinging driven effort but it was well saved by Billy Collings in the Tigers’ goal.
The Barrowmen remained on top coming out of the half-time break and almost made it two when substitute Mayckol Sabino’s attempted lob struck the post.
Sabino came close late on as he raced away down the left but his drive fizzed just past the post.
After the match the Steyning manager praised his side for the result.
Murphy said: “Great to get a win against a strong team away from home.
“Good to see Charlie Romain get the winner after some hard work over the previous games without getting the goals.
“We have had a run of games against the top six teams over the past few weeks but as most managers will tell you, there are no easy games.”
The Barrowmen host second-placed Peacehaven & Telscombe on Saturday and Murphy is expecting a challenge following their previous encounters.
He added: “We entertain Peacehaven & Telscombe on Saturday in another tough match.
“After already playing each other three times this season, both teams should know what to expect.”
Steyning Town: Kelly, Clark, Weston, Levoi, Hurley, Gathern, Bull, Faber, Radmore (Sabino 68), Romain (Bloomfield 85), Hards. Unused: Sabino, Maher, Spano, Trigwell.