Aubameyang turned provider for Arsenal's second, chasing down a Ramsey pass before it went out of touch and crossing for Ainsley Maitland-Niles to smash a header in to double the hosts' lead.
Aubameyang is Arsenal's top scorer this season with 22 and they are through to the quarter-finals of the Europa League.
Arsenal have missed out on Champions League football for the last two seasons, and their poor away record remains a big concerns.
Nevertheless, Emery said the Champions League, Europe's premier club competition, was not his only focus because the Europa League - which he won three times in a row from 2014 to 2016 as manager of Sevilla - also provides the chance for silverware.
"I said to the players today, I'm excited (about) this competition, but it's exciting not only for the possibility to go to the Champions League, but also because it's one title", he said.
"This game was a tricky situation because at 2-0 up, you're through, but they just need one goal".More news: Rosario Dawson Confirms She's Dating Senator Cory Booker!
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"It is not all like we wanted with the control, but I think as a competitive match, we did very well".
The Gabonese striker then proceeded to celebrate by putting on a Black Panther mask, which he was duly booked for by the referee.
"I needed a mask that would represent me", Aubameyang told BT Sport.
"Black Panther.in Africa and Gabon we are called the Black Panthers so it represents me - that's it".
Rennes boss Julien Stephan questioned that decision - as well as another possible sending off for Lacazette in north London and Aubameyang being offside for the crucial second Arsenal goal.