Newcastle's rich seam of form continues and this victory over the team above them in the Zurich Premiership leaves them close to a top four finish and Heineken Cup qualification with all to be decided on the last day of the season.
The Falcons always looked the stronger and more dangerous, underlined by their three tries, seven penalties for Irish fly-half Barry Everitt kept them in contention.
Some trademark slick play by the Newcastle backs left the Irish defence in tatters before Jamie Noon broke clear for his second try .
However, Irish were back in with a chance when Chris Sheasby emerged from under a pile of bodies for what proved their only try. The visitors stayed within one score of snatching victory until the stroke of time when Jonny Wilkinson slotted a penalty to give the Falcons a measure of safety.
The final word went to Everitt with a consolation penalty that ended the match.
The Irish met a Newcastle side hitting form. It was the visitors, though, who had the better of the opening exchanges and two Everitt penalties provided the opening points.
So often Jonny Wilkinson has proved the key to Newcastle's cause and again worked his magic as the first quarter drew to a close. A devastating break gave Noon had an easy run to the line.
Yet for Irish Everitt was in imperious kicking form, landing three more penalties including two when his side were reduced to 14 men after Rob Hoadley was sin-binned. The Newcastle man instantly punished this by landing the penalty. But the last word went to the Falcons as Michael Stephenson broke clear, eluding a tackle on his way to the line. The game seemed fated to turn on the contest between the genius of Wilkinson and the unerring boot of Everitt.
Newcastle: Walder; Stephenson, Noon, Tuigamala, Botham; Wilkinson (capt), Charlton; Graham, Brotherstone, Hurter, Vyvyan, Grimes, Dunbar, Devonshire, Arnold (Lam, 68).
Tries Noon 2, Stephenson, Conversions Wilkinson 3. Penalties Wilkinson 4.
London Irish: Horak; Sackey, Appleford, Hoadley (Venter, 56), Bishop; Everitt, Edwards; Hatley, Kirke (Drotske, 45), Halford (Hardwick, 45), Strudwick (capt), Fahrensohn, Halvey (Wheatley, 50), Pfister (Cockle, 66), Sheasby,
Try Sheasby. Conversion: Everitt. Penalties: Everitt 7. Sin-bin: Hoadley 24.
Referee: Tony Spreadbury (Bristol).