Despite a desperate series of late attacks from London Irish, the fly-half’s three penalties settled a game played in steady rain with try-scoring chances few and far between.
A penalty Mike Catt kept the Exiles in touch but replacement fly-half Ross Laidlaw could only land one of his three second-half shots at goal in the second half.
Newcastle did not even need to call on Jonny Wilkinson, in their squad after groin surgery but not required to rise from the bench.
The result was a major setback for Irish, who were attempting to break into the Premiership’s top four and are one of the sides least disrupted by international calls during the RBS 6 Nations Championship.
As well as the high-profile absentees Colin Charvis and Jamie Noon, Newcastle coach Rob Andrew had a to cope without David Wilson and James Hoyle on England Under-21 duty, while Mathew Tait and Ollie Phillips are with the England Sevens side in Los Angeles.
Matt Burke returned to lead the side from full-back behind a reshaped back-line with Walder taking over at fly-half and a new centre pairing in Mark Mayerhofler and Joe Shaw.
Up front, missing lock Stuart Grimes was still troubled by back spasms, while Andy Buist and Cory Harris stepped into the back-row of a pack that has been short on punch this season.
Newcastle, though, just shaded the first half with and ought to have scored more points from some lively work around the set-pieces.
Walder missed from just inside his own half with one early penalty shot before Owen Finegan and Andy Long combined in a sharp thrust down the blindside before the hooker was bundled into touch 10 metres out.
Another attack off the back of a lineout saw James Grindal put Shaw and then Andy Perry close to the line, with Irish eventually straying offside to allow Walder to put the visitors in front after 18 minutes.
Irish did have men to spare when they won a rare turnover on the right, with Delon Armitage unable to pick Neal Hatley’s pass off his bootlaces.
More dynamic driving forced them into Newcastle territory late in the first-half with Catt levelling the scores with a penalty from 25 metres, but the Falcons finished the half with an encouraging flourish by breaking out of defence and Burke put Anthony Elliott away on a long run down the left before Michael Horak cut him down five metres short.
They continued the pressure after the break with Walder adding a second penalty in the 46th minute after another promising surge from Elliott.
Riki Flutey’s replacement Laidlaw missed from long range in the 48th minute and then hit the outside of a post in the 56th after a rare attacking spell from his side.
Walder, though, had another two shots at goal, missing in the 69th minute from wide on the right before nudging Newcastle further in front 10 minutes from time from an identical position.
After two misses and a knock-on in a promising position Laidlaw finally found the target five minutes from time with a 40-metre effort that set up a furious finish.
All their attacking plays had to come from deep on a sodden pitch, though, and despite some brave work from the impressive Armitage, Newcastle held on to pull 10 points clear of bottom side Leeds.