Trent Robinson's men won 40-34 at HBF Park, with Walker scoring two tries from chip and chases that would have had the best exponent of the art, former star Phil Blake, licking his lips.
Walker had a personal haul of 24 points, which included eight goals from as many attempts, and he was on hand to save two tries with defensive resolve.
The Roosters remain in third position but lost winger Dom Young to a hamstring injury and centre Joseph Manu was put on report and sin-binned for a high shot on Dolphins fullback Hamiso Tabuai-Fidow.
Dom Young was a casualty in the Roosters' win, with a hamstring injury. (HANDOUT/NRL PHOTOS)
The Dolphins lost five-eighth Kodi Nikorima (illness) and prop Tevita Pangai Jnr (calf) on match eve - two of their key strike players - but showcased trademark resilience and skill to take it to the Roosters.
With the defeat, the Dolphins remain eighth on 24 points but are ahead of Canberra and St George Illawarra only by for-and-against after a seventh loss in nine games.
The Roosters had strike right across the park and fired from the kick-off. Centre Joseph-Aukuso Suaalii stormed in, then Walker chipped and chased to score, making the difficult look ridiculously easy.
Incredibly, Walker did it again minutes later. He bamboozled Dolphins forward Felise Kaufusi, running around in a circle, then dinked the ball over fullback Tabuai-Fidow to score a try of daring and beauty.
Dolphins rake Max Plath, their best player, burrowed over from dummy-half and set up one from close range for Kaufusi. A sweeping backline play and sensational catch and pass from centre Jake Averillo led to winger Jamayne Isaako scoring and it was 18-all.
Averillo split the Roosters after the break and Tabuai-Fidow did the rest to give the Dolphins a stunning 26-20 lead. It only lasted four minutes.
Two Dolphins errors, two offloads by Roosters second-rower Angus Crichton and two Roosters tries - one each to Daniel Tupou and Sitili Tupouniua - had the Tricolours ahead 32-26.
A 20m pass by Walker, as ad-libbed as ever, inspired Tupouniua's second but the Dolphins rallied late with a Jack Bostock try in the 71st minute.
Roosters forwards Lindsay Collins and Victor Radley clashed heads in the 16th minute and both went off for HIAs. Only Radley came back. Forward Nat Butcher also sustained a rib injury.
The Roosters, in third position, were also brave and can rest their wounded through a bye next week.
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