Arsenal saw more of the ball but the hard-pressing Marseille had created the better chances until the visitors went ahead on 65 minutes.
Walcott got a helping head from Lucas Mendes, whose dreadful clearance landed to the unmarked Walcott. The England forward finished with aplomb. Marseille had just gone close when Per Mertesacker sliced a clearance off the bar.
The in-form Ramsey added a fine late second, going on a mazy run before drilling a low effort past Steve Mandanda.
Jordan Ayew pulled one back from the spot in injury time after he was fouled by Ramsey, but it was too little too late for Elie Baup’s side.
PRE-MATCH: Ozil gets Gunners CL bow, Thauvin left out – Mesut Ozil shrugged off fitness concerns as Arsenal showed a strong XI, with Thomas Vermaelen back on the bench after injury. Marseille left starlet Florian Thauvin on the bench as he struggles with match-fitness following a controversial transfer from Lille.
22’ – CHANCE: Andre Ayew heads inches wide from a good cross by the excellent Dimitri Payet.
47’ – CHANCE: Rod Fanni flashes a flick and volley combination just wide. Not bad for a right-back.
60’ – CROSSBAR: Payet’s low cross is sliced by Mertesacker, hitting the bar but landing in Wojciech Szczesny’s arms.
65’ – GOAL: Walcott thrashes it home after a terrible error by Mendes, whose awful defensive header went straight to the Arsenal man. Gibbs with the initial cross.
83’ – CHANCE: Ozil smacks a low drive inches wide after an error from Fanni.
85’ – GOAL: A fine strike from Ramsey, who dribbles past several defenders before hitting it home. Gibbs with the pass.
90+2’ – GOAL: Jordan Ayew converts from the spot after he is brought down by Ramsey.
Marseille have only won one of 10 matches against English teams.
This was Arsenal’s sixth win in a row in France.
Ramsey has scored six goals in seven matches this season.
TALKING POINT: Arsenal sweat the small stuff – Despite not playing particularly well, and in face of stern opposition, Arsenal were able to grind out a tough away win. And Ozil barely got involved.
MAN OF THE MATCH
Kieran Gibbs (Arsenal): A bombarding performance from the left-back, who finally showed the mature performance we’ve been waiting for. Two assists as well as a solid shift defensively.
Marseille: Mandanda 6, Morel 6, Nkoulou 6, Mendes 5, Fanni 6, Imbula 6, Romao 6, Payet 7, Valbuena 7, A.Ayew 6, Gignac 6; Subs: Khlifa 6, J.Ayew 7, Thauvin NA
Arsenal: Szczesny 7, Gibbs 8, Koscienly 6, Mertesacker 6, Sagna 6, Flamini 6, Wilshere 6, Ramsey 7, Ozil 6, Walcott 7, Giroud 5; Subs: Monreal NA, Miyaichi NA
THE MATCH IN A TWEET
Arsenal beat their cousins in Marseille as the Gunners get the breaks for once. And Mesut Ozil had little to do with it.