The extension has five stations, including a 312-space park-and-ride stop at Cheeverstown, and is expected to boost passenger numbers on the Luas network by around 2 million to almost 30 million this year.
Citywest was developed as a public private partnership (PPP) between the Railway Procurement Agency, South Dublin County Council, and a private sector consortium. Around 55% of the Euros 150 million budget came from private landowners along the route.
At the opening, Varadkar also confirmed that a decision will be made on the future of proposals for a link between the Red and Green lines and the Metro North project at the end of September as part of a new National Development Plan. The future of these and several other Dublin rail projects remains in the balance following the Irish government's recent bailout by the European Union and International Monetary Fund.