Villa's manager celebrated his 100th win in charge after a determined performance at the Stade Pierre-Mauroy, where his side absorbed heavy pressure before finding the decisive breakthrough just after the hour.
The winning moment arrived through Ollie Watkins in the 61st minute, who ended an eight-match scoring drought with a composed header. A high ball forward from Ezri Konsa was flicked on by Emiliano Buendia, allowing Watkins to lift his header over goalkeeper Berke Ozer.
Villa almost doubled their advantage moments later when Amadou Onana curled an effort from the edge of the penalty area that struck the angle of post and crossbar.
Speaking after the match, Emery said his players had delivered exactly the kind of performance he demanded.
"We played very seriously," he told VillaTV. "We were organised, we defended strongly and tried to be comfortable without the ball. At the same time we wanted to control the game and create transitions when we had possession, and we did that."
Emery acknowledged the challenge of European away fixtures and praised his players for following the tactical plan.
"We respect this competition because every match in Europe is difficult, especially away from home," he said. "We didn't create a lot of chances, but the chances we had were clear ones."
The Spaniard also emphasised the need for more attacking contributions across the squad.
"We need goals and numbers from the attacking players - Watkins today, but also Morgan Rogers, Jadon Sancho, Leon Bailey, Emiliano Buendía and the midfielders. Everyone has to contribute."
Despite the positive result, Emery warned that the tie was far from settled.
"This result is good, but it is only the first leg. We still have another 90 minutes."
Defender Konsa echoed that message, insisting Villa must remain focused ahead of the return leg at Villa Park on 19 March.
"That was a victory we really needed," Konsa said. "It hasn't been going too well for us recently, but we showed what we are about. We won the game, but we cannot get comfortable - we have to finish the job next week."
Before that decisive second leg, Villa will turn their attention back to domestic action with a demanding trip to face Manchester United on Sunday.
Sebastian Hoeness has admitted his side “briefly lost composure” during a costly spell as VfB Stuttgart slipped to a 2-1 defeat against FC Porto in the first leg of their UEFA Europa League round of 16 clash on Thursday night.
David Moyes has urged Everton to maintain their momentum as the Premier League season enters its decisive final stretch, insisting his side will not "take their foot off the pedal" in the race for a strong finish.
Liam Rosenior has admitted his side must learn how to handle difficult moments during matches if Chelsea FC are to fulfil their potential, following a damaging 5-2 defeat to Paris Saint-Germain in Paris.
Unai Emery has insisted Aston Villa must stay disciplined and control their emotions as they prepared to face LOSC Lille in the first leg of their UEFA Europa League Round of 16 tie tonight.
