Kerr was sidelined by a calf injury sustained in training on Wednesday and will also miss the co-hosts' second Group B match against Nigeria in Brisbane next week.
Catley said the players were "heartbroken" by the news but the defender replaced Kerr as captain as well as penalty taker, converting a 52nd-minute spot kick to give the Matildas the win.
"We had to really gather ourselves pretty quickly. But we used her spirit and used the fact that she wasn't able to be out there with us to help us push on," the defender told reporters at Stadium Australia.
"That all adds to what we already bring and I think that's what it's going to take for as long as maybe she misses, but she's got a role still whenever she plays, she's a master for us.
"She's so, so important, she's our spiritual leader. Sam was involved non-stop, from the first chat in the locker room to the last chat."
Kerr, who is the all-time leading goalscorer for her country with 63 goals, watched the game from the bench at Stadium Australia, which was filled with a record crowd of 75,784 fans.
"I wanted to share this with everyone so there is no distraction from us doing what we came here to achieve," Kerr posted on Instagram barely an hour before kick-off.
"Of course I would have loved to have been out there tonight but I can't wait to be a part of this amazing journey which starts now."
Australia kick off the tournament on a wave of momentum having won nine of their previous 10 games, including a 1-0 win over France in a friendly last Friday and a 2-0 win over England in April that ended the Lionesses' 30-game unbeaten streak.
There was some injury speculation around Kerr after the France game when she was spotted with an ice pack on her hamstring after she was taken off in the 62nd minute.
This is the fourth World Cup for Kerr, who spoke about the pride of playing on the global stage in front of a home crowd.
"To be at home and get the feel for it, walk down the streets and see people that are excited or flying around the country to watch us, it's nice to be able to feel the love," she said on Wednesday.
"But also we're really proud to bring this World Cup home and let Australia experience what we do all around the world."
Thursday's match against Ireland, making their first appearance at a major tournament, was expected to be played in front of a capacity crowd at Stadium Australia. Kerr was in the dugout and linked arms with the team's substitutes during the singing of the national anthem.
Fans entering the stadium were crestfallen to hear the news.
"Oh, that's not good, that's very bad, that's awful, she's the best player we have so that’s bad for us," said supporter Matt Starr.
"Very sad, we're very sad, we came to see Sam Kerr but still Australia to win," said fan Sue Moar.
Lisa Schibezi called the news "devastating" and hopes Australia make it through the group stage so Kerr has the opportunity to play in Sydney.
"Because this is our only chance to see her in Sydney so if they don't make it through, we don't get to see her play in Sydney, so just really really hope she's okay and we get to see her again," she said.
See the stats from Australia's first match of the World Cup against Ireland at Flashscore
