Meredith left Bradford City to sign a two-year deal with the English Championship side in May.
The Australian fullback was in demand from several Championship clubs, after starring in League One for several years, but he has revealed a chat with manager Neil Harris and one with Harris’ old teammate Cahill convinced him to head south.
Cahill is regarded as one of Millwall’s greats having spent eight years there after joining the club in 1997 from Sydney United.
The 37-year-old made more than 200 appearances for the Lions and famously helped them reach the 2004 FA Cup final, before his move to Everton.
“I had a meeting with the manager Neil Harris in London and he showed me a presentation on Millwall, he showed me a presentation on myself,” Meredith told The World Game.
“They’d really done a lot of research. He convinced me that he wanted me in the team, to play week in, week out, be number three and I was just really impressed.
“I wanted to make the change and he also said speak to Tim Cahill. Apparently Neil Harris used to room with Tim Cahill when Tim played for Millwall.
“So I messaged Tim and asked him and he said: 'You should go there, you’d love it'. So that was another factor.
“He said he’d loved his time there.”
Meredith has made a solid start in the Championship, starting in all five of Millwall’s league fixtures.
The newly-promoted Lions currently sit in 17th place after one win, two draws and two losses so far this season.
Millwall defeated Meredith’s former club Bradford City 1-0 at Wembley in the League One playoff final to clinch promotion into the Championship.
The defender admits it was somewhat weird to swap the Bantams for the team that ended their promotion dream.
“It was a bit strange at first going from the club that had lost in the playoff final to the club that had beaten us,” the 29-year-old said.
“But everyone has made me feel really welcome at Millwall. The facilities are really good, the lads are really good, the training’s very good.
“I’m just really enjoying Championship football.”
After arriving in the UK as a 17-year-old and signing for Derby County in 2006, Meredith has worked his way up the football pyramid the hard way, going from the Conference North and the League of Ireland Premier Division to then League Two, League One and now eventually the Championship.
His journey has included two caps for the Socceroos back in 2015.
“I had to work really hard from Conference North upon year, upon year, upon year, just work, work, work and finally get in a position where I’m in a good league,” he said.
“I’m really grateful and happy. I’ve never been this happy – I feel I’ve found my level.”