In his first game for 314 days, injury-stricken halfback Walker struck David Klemmer in a cannonball tackle, bringing the prop to the turf by entering the fray late and targeting his legs.
The dangerous first-half shot put a damper on an otherwise strong return from Walker, who gave the Roosters the halftime lead with a field goal and then laid on a crucial try in the second half.
Sporting headgear on return from his latest concussion, Victor Radley flew in for the game-sealing try in the final three minutes by grabbing a high inside ball from James Tedesco.
The Roosters will be hoping for an uninterrupted two months of Walker magic on the run to finals as they move back into the top eight with Saturday night's win at Kogarah Oval.
But Walker will face suspension if he receives anything more severe than a grade-one charge, with the last man cited for a cannonball tackle, Karl Lawton, rubbed out for two games.
A ban would be a tough pill to swallow for Walker after last month's broken thumb delayed his return from the anterior cruciate ligament injury he suffered in September.
The two sides scored a staggering five tries between them in a frantic first 17 minutes.
Walker's edge put Daniel Tupou over for two tries as the veteran feasted on Tyrell Sloan, but Saints' Sione Finau gave his own opposite man, rugby convert Mark Nawaqanitawase, the same treatment.
But after coming back from the sin bin, Walker put the Roosters up by a point with a field goal from 12 metres out in the final minute of the first half.
His beautiful flat ball to Billy Smith gave the visitors their fourth try just after the break and reminded the NRL world just what they'd missed while the skilful 23-year-old was out injured.
After some good chances, including a Jacob Liddle knock-on over the line, the Dragons finally had second-half points through a lovely Kyle Flanagan short pass to Jaydn Su'A on the right.
But as in last week's loss to Canberra, they had to settle for gallant defeat and are set to finish the weekend four competition points out of the top eight.
