Joe Schmidt's men are challenging for honours domestically, they currently sit top of the RaboDirect PRO12 table, and in Europe with a home Heineken Cup quarter final coming up against the Blues next month.
And Thorn, who had been plying his trade in Japan with Fukuoka Sanix Blues, knows full well the importance of the next three months in his and Leinster's season.
"I'm pretty excited to be here having been to Dublin a few times with the All Blacks," Thorn told www.leinsterrugby.ie
"This is an exciting time, Leinster are a great club who play some good rugby. They've been very successful in recent years.
"It's a challenge to come here, perform well and honour the jersey and the fans and try my best.
"I had a good time in Japan but I'm really happy about this little adventure for the next couple of months."
Thorn brought the curtain down on a much-decorated international career that saw him represent Australia at Rugby League as well as the All Blacks in Union by hoisting the World Cup trophy aloft at the end of last year.
And while the 37-year-old has barely stopped to catch his breath since then, the second-rower is adamant he has what it takes to contribute in the season run-in.
"The World Cup seems like a long time ago, it was massive for me, a real a career moment," he added.
"But the Monday afterwards I went home, packed up my house and by the following Monday I was in Japan and started the next weekend, I haven't stopped at all.
"But the fans here have a great reputation, there will be great atmospheres and hopefully, if selected, I can be amongst it."
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