Koscielny netted the third in Arsenal's 3-2 win over West Brom on Sunday that means the north London club will enter the competition at the group stage, avoiding an early-season qualifier.
The former Lorient man believes that is side fully deserved their place in the league after a tough campaign.
Koscielny told Arsenal's official website: “If I score with my left foot, right foot or with my head, the most important thing is that it's a goal and it was for the team.
"This goal was important and I am very happy for the fans, the team and the boss because we have all worked hard to be here today.
"It was very important to win because we want to play in the Champions League next year. We did the job on the pitch.
"Maybe it wasn't our best game of the season but the most important thing was to get the three points."