The Gunners were largely outplayed by a visiting side desperate to start the new year with a surprise result to lift themselves out of the relegation zone.
Steve McClaren's men certainly created more chances but they were undone when Laurent Koscielny scored his third of the season from close range to secure a 1-0 win for the hosts.
Petr Cech, fresh from sealing the Premier League clean-sheet record, kept out a number of Newcastle chances - most notably Georginio Wijnaldum's early second-half shot.
And it was Arsene Wenger and his players left smiling at the full-time whistle as Koscielny's effort, coupled with Leicester's goalless draw at home to Bournemouth, saw them move clear at the summit.
Twice in the opening two minutes Hector Bellerin was freed down the right for the hosts, using his pace to get into a good crossing position.
The first was turned behind for a corner before Alex Oxlade-Chamberlain failed to make meaningful contact with the second as Wenger's men looked to strike early.
Arsenal were on top but it was their goalkeeper Cech who was forced into the first save of the contest, diving to his right to keep out Wijnaldum's header.
The visitors were enjoying a period of possession as Arsenal struggled to gain momentum, with Olivier Giroud's blocked effort on 37 minutes their first chance of the game.
Cech then had to make two routine saves from Aleksandar Mitrovic and Wijnaldum before half-time and was back in action shortly after the break.
This time Wijnaldum was clean through when he was denied by Cech before Mitrovic turned over Ayoze Perez's cross from less than six yards out.
Arsenal responded but Aaron Ramsey could not turn home Mesut Ozil's cross, with Rob Elliot in the Newcastle goal easily holding onto the midfielder's effort.
With Elliot earning the wrath of the home fans for perceived time-wasting, Wenger started pacing his technical area and remonstrating with referee Anthony Taylor and fourth official Stephen Martin.
But it was still McClaren's side that was creating, and wasting, the chances - this time Chancel Mbemba heading well over the bar from the centre of the area.
All of those missed opportunities came back to haunt the Magpies as Koscielny tapped home from close range with a little over 15 minutes remaining.
Ozil swung in a corner which Giroud eventually nodded towards goal, with France colleague Koscielny nipping in ahead of a dozing Perez to put the Gunners ahead.
Newcastle still pushed on but Mitrovic again missed the target with a difficult header before Ramsey and Ozil both came close to a clinching second goal for the hosts.
Source : PA
Source: PA