Unai Emery's side seized control of the tie with a dominant first-half performance at the Emirates Stadium.
Ramsey opened the scoring with a cool finish to cap a flowing move and the Gunners were further ahead before half-time when Napoli defender Kalidou Koulibaly deflected Lucas Torreira's shot into his own net.
Arsenal couldn't add to the lead after the break, but they had done enough to put themselves in pole position ahead of the second leg in Naples on April 18.
It was a much-needed success for Emery, who this week called on his players to embrace the pressure of regaining their Champions League status after two successive seasons out of Europe's elite club competition.
With Arsenal sitting fifth in the Premier League after Sunday's damaging defeat at Everton, the Gunners can no longer rely on their domestic fortunes to qualify for the Champions League.
That gives the Europa League extra importance, underlining why Emery had played strong line-ups in the tournament all season to keep the option of reaching the Champions League by lifting the trophy.
Having won the Europa League three times during his tenure as Sevilla boss, Emery knows the value of a first leg lead and he sent out an attacking line-up featuring Pierre-Emerick Aubameyang, Alexandre Lacazette and Mesut Ozil.
Emery's men were quickly on the front foot and Koulibaly showed why he is a target for Manchester United with a two brave blocks to stop shots from Aaron Ramsey and Ainsley Maitland-Niles.
Despite Koulibaly's best efforts, Arsenal needed just 15 minutes to take the lead.
A stylish move carved Napoli open as Ramsey and Ozil exchange passes in midfield before Lacazette fed Maitland-Niles.
Ramsey had continued his run into the Napoli area and the Wales midfielder met Maitland-Niles' pass with a composed close-range finish for his sixth goal of the season.
It was the perfect way for Ramsey to announce himself to an Italian audience ahead of his close-season move to Juventus.
Torreira is one of the midfielders who will take over from Ramsey and the Uruguayan showed why that should be a smooth transition as he helped double Arsenal's advantage in the 25th minute.
Tigerishly dispossessing Fabian Ruiz inside the Napoli half, Torreira accelerated towards the penalty area, cleverly checked back to open up more space and drilled a low shot that took a hefty deflection off Koulibaly as it looped into the net.
Napoli are trailing a distant second in Serie A behind Juventus and had endured disappointing results in their previous two games.
The lack of cohesion and confidence in his team made it a far different experience forRead More
