Stella signed on a one-year deal on Friday night but is still waiting for international clearance.
However, he played and scored in a 3-1 bounce game win over Falkirk today at Ibrox.
The 21-year-old from Melbourne said: “I am delighted to sign for Rangers. It’s a great move for me to join such a big club and I can’t wait to get started.
“I knew of Craig Moore, Tony Vidmar and Kevin Muscat. I’m happy to be the latest Australian to come to Rangers.”
Stella, who has Italian parents, has been away from home for four years having started in the youth system in Chievo and then moved to Siena.
He said: “I had a few problems with Siena. I had another year of my contract to run but we came to an agreement and I was a free player.
“There was then an opportunity to come here on trial and I couldn’t say no.
“So was here for two weeks and then signed a deal last Friday.
“I was with Siena for about two and a half years. Initially I signed as a youth player but in the second year I moved into the first team squad.
“Unfortunately in Italy they don’t tend to use young players so I never made my first team debut but it was nonetheless I good experience to train with a Serie A club.
“I played for the under-21 side and then I went on loan and played in the Third Division and that was good experience too.
“But I’m delighted to be here now and hopefully I can be a success.”