Transport for Greater Manchester said the new Metrolink line to Wythenshawe and Manchester Airport will launch before the end of 2014, some 12 months ahead of schedule.
Trams will start to run along part of the route from Monday 23 June as the first stages of the testing and commissioning process.
The 14.5km route, delivered by the MPT consortium, is one of the biggest live civil engineering projects in the country.
Several major purpose-built structures have been erected as part of the programme, including a viaduct over the Mersey Valley, two new bridges over the M60 and M56, and the Ringway Road dual carriageway and underpass at Manchester Airport.
All of the existing highway and street lighting and road signs along the route have been renewed and urban realm improvements have been made around each of the line's 15 stops.
A 300-space Park & Ride facility at Sale Water Park, free for Metrolink passengers, will serve the line.
Services will initially run between Manchester Airport and Cornbrook every 12 minutes. They will start to run through the city centre once the Second City Crossing is complete in 2017.
Cllr Andrew Fender, chairman of the TfGM committee, said: "The sheer scale of the challenges this project presented make its early completion a truly phenomenal achievement.
"To be so far ahead is down to several marginal gains adding up to a significant result: the early delivery of a number of lines allowed us to move resources onto the line earlier; lessons learnt during the early phases of the expansion drove efficiencies across work areas; creating a desktop simulator cut the timescales for driver training in half.
The Airport line will bring the total size of the Metrolink network to 92.5km serving 92 stops.