The hosts went behind against the run of play after Martin Ellingsen pounced on some passive Arsenal defending to curl a bouncing effort past Bernd Leno midway through the first half. But a frustrating opening 45 minutes ended with a somewhat fortunate equaliser, as Kristoffer Haugen prodded the ball into his own net following good work by Granit Xhaka and Joe Willock, before a second Molde own goal and a Nicolas Pepe effort in seven second-half minutes put the Gunners firmly in control.
Willock added a layer of gloss to the score in the closing stages when he stroked the ball high into the net after some sloppy play by the tiring Norwegians.
Winning despite a mediocre performance is a good trait to have, and in the end, the North Londoners won the game at a canter after shifting through the gears in the second half.
The Molde opener was a poor goal to concede and came after needless overplaying at the back left Leno boxed in with nowhere to go, while the Arsenal press was played through far too easily for manager Mikel Arteta's liking in the first half.
Manager rating out of 10
6 -- It was an ordinary performance from what was an under-strength, experimental Arteta side, but this system seems to lack a creative link between midfield and attack, with Dani Ceballos and Granit Xhaka often way too deep to knit things together in the final third.
Player ratings (1-10; 10 = best, players introduced after 70 minutes get no rating)
GK Bernd Leno, 6 -- It was an excellently placed shot that beat him for Molde's goal, but the German international will be disappointed he couldn't keep out Ellingsen's low effort from distance that he saw all the way.
DF Ainsley Maitland-Niles, 7 -- An authoritative display at right-back in which he looked dangerous in the opposition half while being assured and compact in his own. Replaced by Cedric Soares just after the hour.
DF Shkodran Mustafi, 6 -- An occasional threat from set pieces and perhaps the more assured of Arsenal's central defensive pairing in a poor first half but recovered in the second period.
DF David Luiz, 5 -- The centre-half didn't even attempt to close down Ellingsen as the forward set himself up to fire Molde into a first-half lead, and he had a tough time dealing the slippery Ohi Omoijuanfo at times. Booked for leading with his arm in an aerial duel in the second half.
DF Sead Kolasinac, 6 -- It was a laboured display that lacked urgency and any remnant of attacking presence in the first half, and while the Bosnian was a more regular fixture in the final third, in the second half he simply had to score from inside the 6-yard box with the goal at his mercy.
MF Granit Xhaka, 6 -- Played a part in the Arsenal equaliser when he carried the ball through the Molde half before releasing Nketiah in the penalty area. Brought off for Kieran Tierney in the 80th minute as Arsenal switched to a back three.
MF Dani Ceballos, 6 -- He certainly possesses enough talent to unlock stubborn defences, but the Real Madrid loanee failed to get himself in enough dangerous positions to create anything of significance. A quiet outing came to an end after 79 minutes when he was replaced by Mohamed Elneny.
MF Joe Willock, 7 -- The 21-year-old played a major part in both Molde own goals, as his powerful running forced Haugen to bundle the ball into his own net for 1-1, before his shot was then stabbed home by Sinyan to put his side ahead. His strong performance was capped off in the 88th minute when he emphatically fired home inside the penalty area.
MF Nicolas Pepe, 6 -- A poor display in which the winger constantly dallied on the ball and gifted possession away needlessly, but the Ivorian scrapes a six after stroking home Arsenal's third in accomplished fashion.
MF Willian, 6 -- The Brazil international had fleeting moments of looking dangerous, but the former Chelsea man probably had an eye on Sunday's Premier League clash with Aston Villa and he was subbed off for Bukayo Saka after 63 minutes.
FW Eddie Nketiah, 6 -- Unfortunate to be denied a goal by the offside flag when he tapped home from close range late in the first half, before his pass across the penalty area was dispatched into his own net by visiting defender Haugen a few minutes later.
DF Cedric Soares, 6 -- Came on and injected some pace and purpose down Arsenal's right flank.
MF Bukayo Saka, 6 -- Found space in the penalty area before pulling the ball back for Pepe to slot home and put the Gunners in the driving seat. Booked in the 77th minute for a trip.
MF Mohamed Elneny, NR -- Solidified the Arsenal midfield in his short cameo.
DF Kieran Tierney, NR -- Came on to pack out the home defence for the final 10 minutes and see things out.