The striker says it was a big win for the side with Bayern Munich coming up in midweek.
The Gunners ran out 3-0 winners at the Liberty Stadium on Saturday afternoon, with goals from Giroud, Laurent Koscielny and Joel Campbell seeing them to all three points.
It was another big result for Arsene Wenger’s side to continue their fine run of form of present, with the win keeping them joint top of the Premier League table alongside Manchester City.
They face Bayern Munich in a crunch Champions League clash of Wednesday and Giroud says the win over the Swans was much needed ahead of that game.
“It was definitely a good win,” he told Arsenal.com.
“We needed this win before the big game on Wednesday. We started slowly but we were creating chances to score. We needed to wait until the second half to put it in and to score three goals and even more, get another clean sheet.”
The striker was also keen to praise his side for their efficiency in both defence and attack in the game.
The win over the Swans flattered Arsenal somewhat, with the home side having had much of the better play in the first half and unlucky not to take the lead when Bafetimbi Gomis spurned a big opportunity to open the scores.
In contrast, the Gunners were clinical when the chances came their way and Giroud praised their efficiency.
“I said it was not easy in the first half but we succeeded to play our game,” he added.
“[We got] more in between the lines with more technique and we were efficient up front and at the back as well so we are really pleased with this game so hopefully we can win the second leg as well.”