The Gunners raced into a four-goal lead inside the first 27 minutes, with Kai Havertz netting the opener on the 13-minute mark shortly before Gabriel Jesus, Bukayo Saka and Gabriel Martinelli all made the net ripple.
Martin Odegaard then added a fifth just before the interval to help Arsenal become the first English club in Champions League history to boast a five-goal lead at half time, before substitute Jorginho converted from the penalty spot four minutes from the end to seal an emphatic and thoroughly deserved win for Mikel Arteta's side.
Arsenal cannot be caught at the summit of Group B with a game to spare, as they sit four points clear of second-placed PSV Eindhoven, who came from two goals down to bet Sevilla 3-2 in Spain.
Meanwhile, Lens - who were condemned to their heaviest European defeat by the Gunners - sit three points further back in third and must beat Sevilla at home in their final group match, as well as hope that Arsenal beat PSV, if they wish to reach the last 16.
Arsenal dominated proceedings early doors and they were rewarded with the opening goal scored by the man who netted the match-winner in a slender 1-0 Premier League victory at Brentford last weekend.
Indeed, Havertz netted his second goal in as many games and became the 100th different player to score a competitive goal at the Emirates when he poked home from inside the six-yard box after Jesus rose above Kevin Danso to head the ball into the German's path.
Jesus then added a second with a brilliant sidestep and finish into the bottom corner from inside the area, before Saka chested the ball into the net two minutes and 22 seconds later after Brice Samba could only parry Martinelli's shot straight to Arsenal's No.7 in a central position.
Martinelli was a livewire down the left flank and his first-half showing was rewarded with a superb curling strike into the far corner to add a fourth for Arsenal, before Odegaard capped a sweeping move forward with a powerful first-time volley into the bottom corner from 12 yards after receiving a delicate cross from Takehiro Tomiyasu down the right.
Lens looked all over the place at the back, but they enjoyed a decent spell of possession towards the end of the first half and came close to pulling one back when Elye Wahi - who scored and provided an assist in a 2-1 win over Arsenal in the reverse fixture - fizzed a powerful shot across the face of the six-yard box from a tight angle, shortly before Facundo Medina smacked a 25-yard strike against the post.
Five changes were made for the start of the second half between the two teams - two for Arsenal with Ben White and Jakub Kiwior replacing Tomiyasu and Oleksandr Zinchenko in defence, while Deiver Machado, Adrien Thomasson and Neil El Aynaoui all came on for Lens in a triple change.
Arsenal's intensity dropped slightly after the break, and they rarely threatened Lens' goal until the 66th minute when Samba got down well to save a stroked effort from Odegaard on the edge of the area, after Havertz did brilliantly to weave out of trouble on the byline and produce a cross.
Saka, Jesus and Declan Rice all came off to rapturous applauses from the home supporters as Arsenal saw out the contest with ease, and Arteta's side came close to adding a sixth when White glanced a header just over the crossbar at the near post following a corner.
However, Arteta's side were able to celebrate a sixth goal on the 86-minute mark when Jorginho coolly converted from the penalty spot after Abdukodir Khusanov was deemed to have handled inside the box following a VAR review.
Arsenal will look to build on their emphatic victory and extend their winning run in all competitions to five matches when they play host to Wolverhampton Wanderers in the Premier League on Saturday, while Lens will attempt to bounce back when they face Ligue 1 basement club Lyon in their next match.