The Gunners warmed up for the Premier League campaign with four wins from four against Indonesia, Vietnam, Nagoya Grampus and Urawa Red Dragons - netting 19 goals in the process.
Arsene Wenger's side will be attempting to raise the bar again at the weekend when they take on the likes of Napoli, Galatasaray and FC Porto in the Emirates Cup.
Koscielny said: "We won all our games so that's good for confidence. We had a lot of training and all the players trained very well and gave themselves for the team.
"Pre-season is very important for the Premier League. It's a long season so we need to be fit - I think we did well.
"The wins give us some confidence, and it's good for the next games - the Emirates Cup, [the friendly] against Manchester City and the start of the season."