The 23-year-old midfielder joined United from Crewe last month and his seven-figure fee - the first time the club have paid such an amount for a player since they signed Richard Cresswell in 2005 - has installed him as a beacon of hope to Leeds' fans.
On a day which saw them celebrate the start of an advertised new era following the summer ousting of controversial former chairman Ken Bates, it was perhaps fitting for them that Murphy should make a late run into the box and down last season's play-off semi-finalists.
Prior to Murphy's intervention a draw was on the cards, with Ross McCormack having cancelled out Leonardo Ulloa's opener for a Brighton side coming to terms with changes of their own, with manager Oscar Garcia having replaced Gus Poyet over the summer.
But the crowd of 33,432 would be left celebrating come the end as Murphy struck, giving former Barcelona man Garcia a rude awakening to life in the hustle and bustle of the SkyBet Football League.
Had Paddy Kenny not made three brilliant saves to deny them it could have been a different story, but with Leeds having squandered chances of their own, it was always going to settle with the side which could make an opportunity count.
Leeds had not appeared so sure-footed early on, however, and it was Brighton who made the first impression as Andrea Orlandi forced Kenny into action from 25 yards.
The early stages certainly gave a nod to Garcia's philosophy - Brighton were happy to roll the ball around - and with 13 minutes gone it bore fruit as Ulloa haunted Leeds again.
The ex-Almeria man booked Brighton's play-off place with a last-minute winner against Leeds in April and was on the spot again today, nipping ahead of Tom Lees to tuck an Andrew Crofts cross under Kenny's body.
Ulloa's strike briefly took the sting out of the atmosphere, but within five minutes Leeds were level.
Michael Tonge dug out a cross from wide on the right, and when Luke Varney's flick fell to McCormack, the Scotland international did the rest from just inside the box.
The goal appeared to give Leeds an assurance they had lacked early on and Murphy was unfortunate to see a 25-yarder flash wide, while fellow debutant Noel Hunt lifted one over from six yards as he fell under pressure from Matt Upson.
Clear chances dried up after that and it was not until the 55th minute that either goal was threatened again - Varney cutting in on the counter attacking but fluffing his lines and dragging wide.
Brighton had been largely contained since their goal at that point, but suddenly reintroduced themselves to the game at the three-quarter mark with only Kenny stopping them from regaining the lead.
Substitute Will Buckley cut in from the right and pulled back for Crofts, whose instinctive first-time shot was well saved by Kenny, but the former Republic of Ireland international had to be even better on the follow-up as he smothered an Inigo Calderon strike at his near post.
Tonge was then left in a heap and appealing for a penalty as Leeds looked to regain some momentum, while substitute Poleon could have put them ahead without the need for a spot-kick had he done better when hooking a loose ball goalwards.
Poleon - rated highly by McDermott - then nodded a cross wide from six yards as United sought a second, which really should have arrived when Paul Green crashed over after Tomasz Kuszczak parried another Poleon shot in the 90th minute.
Even then there was time for Kenny to deny Buckley with a stunning two-handed stop, before Murphy ran on to a Matt Smith flick to beat Kuszczak from six yards.M