The Gunners have also avenged their FA Cup defeat to Southampton at the weekend despite falling behind after three minutes to Stuart Armstrong's sweet strike.
Manchester City have thrashed West Brom 5-0 to move back top of the Premier League as Arsenal aided their push towards the European places with a 3-1 win at Southampton.
City have now won 11 consecutive games since West Brom earned a shock 1-1 draw at the Etihad last month.
Pep Guardiola's men have hit top form since and did not miss the presence of the injured Kevin De Bruyne in blowing away the Baggies by scoring four goals before half-time.
Ilkay Gundogan opened the floodgates by curling home from the edge of the box before Joao Cancelo's controversial strike doubled City's lead.
The West Brom defence was distracted by a wrongly raised offside flag before the Portuguese full-back found the net, but the goal stood after a VAR review.
Gundogan then took his tally to seven goals in his last eight league games before Riyad Mahrez and Raheem Sterling rounded off the scoring.
"There's not really a secret," Gundogan said of his scoring streak. "I'm just in the right spaces at the right moment. I'm in a bit more of an offensive role, if I get the chance close to the box I try to make the right decisions."
West Brom have now conceded 17 goals in Sam Allardyce's four home games in charge as they remain second bottom of the table, six points off safety.
Arsenal on the rise
Guardiola's former assistant Mikel Arteta is also enjoying a fine run of form as Arsenal have taken 16 from the last possible 18 points.
The Gunners avenged their FA Cup defeat to Southampton at the weekend despite falling behind after three minutes to Stuart Armstrong's sweet strike.
Nicolas Pepe quickly levelled before Bukayo Saka rounded Alex McCarthy and slotted home to give the visitors at half-time lead.
"I think we were good from the start. We conceded a goal from a corner but responded straight away," said Arteta.
"It showed a lot of intelligent and resilience from the team in the way they managed the game."
Alexandre Lacazette sealed a vital three points 18 minutes from time as Arsenal moved up to eighth and within five points of the top four.
West Ham go fourth
West Ham occupy the fourth Champions League place as Tomas Soucek scored twice in a 3-2 win at Crystal Palace.
The Hammers suffered an early setback when Wilfried Zaha put Palace in front after just three minutes.
But the stronger mentality that David Moyes has lauded in West Ham this season showed as Soucek struck twice in 16 minutes to turn the game around.
Only Manchester United's Bruno Fernandes has scored more Premier League goals from midfield than the Czech since he joined from Slavia Prague a year ago.
Craig Dawson headed in Jarrod Bowen's corner 25 minutes from time to make it 3-1 before Michy Batshuayi scored a late consolation for Palace.
A sixth consecutive win in all competitions takes Moyes's men above Liverpool in the table and Jurgen Klopp's struggling Reds will be wary of their trip to the London Stadium on Sunday.
At the other end of the table, Newcastle lost 2-1 at home to Leeds to stretch their winless run to 11 games
"This league is demanding and cruel at times," said beleaguered Magpies boss Steve Bruce.
Raphinha slotted home Rodrigo's cut-back to give Marcelo Bielsa's men a deserved half-time lead.
Miguel Almiron levelled with Newcastle's first goal for five games early in the second half, but parity lasted only four minutes before Jack Harrison's sensational finish with the outside of his left foot claimed all three points for the visitors.
Newcastle have a seven-point cushion over the bottom three, but have now played two games more than Fulham in 18th.