The line will operate in a dedicated above-ground right-of-way, much of it within Finch Avenue, segregated from street traffic.

[18] In April 2012, Metrolinx proposed to start construction on the Finch West LRT in 2015, with the line opening in 2018.

[13] By November 2012, when the city and province signed an LRT master agreement, construction for the line was to begin in 2015 for completion in 2020.

[19] In May 2017, Metrolinx confirmed that it had entered into an agreement with Alstom to build 17 (later revised to 18)[12] light rail vehicles for Line 6 Finch West.

[20] In September 2017, Metrolinx announced the line would not open until 2022 at the earliest, blaming the delay on uncertainty with the Bombardier vehicle supply.

[22][23][24] After consultation with Mosaic on a construction schedule, Metrolinx delayed projected completion of the line to 2023, ten years after the originally announced date.

[25] That May, Infrastructure Ontario and Metrolinx announced that Mosaic had signed a contract to design, build, and finance the construction of the line and stations, and to maintain them for 30 years after their initial opening.

[31][32] By late October 2020, the first rails were being installed at the line's new maintenance and storage facility,[33] with the first vehicles scheduled to arrive in mid-2021.

[29] In December 2020, Mosaic Transit Partners awarded Bombardier Transportation a 30-year contract to maintain Line 6's light-rail vehicles as well as wayside systems such as track and overhead catenary.

[29] In late January 2022, the first vehicle test on the Finch West LRT occurred at its maintenance and storage facility.

[35] In February 2022, an LRV made a 700-metre (2,300 ft) trip from the MSF along York Gate Boulevard onto Finch Avenue.

[35] By May 2022, Mosaic Transit Group had laid about 35 percent of the 25.6 kilometres (15.9 mi) of total track required to complete the line.

[40] By late June 2023, canopies have been fully or partially installed at Sentinel, Tobermory, Driftwood, Jane and Finch, Norfinch/Oakdale, Signet Arrow, Duncanwoods, Rowntree Mills, Stevenson, Albion, Martin Grove and Westmore stops.

[44] By mid-September 2024, construction had finished for the two terminal stations and all surface stops; the testing and commissioning phase remained to be completed.

Mosaic expected the TTC to "facilitate effective implementation of maintenance and operational requirements once the line commences service".

[11] In December 2023, the TTC made the assumption for budget purposes that Line 6 would open no earlier than September 2024.

[4] From west to east, the 10.3-kilometre (6.4 mi)[5] line will run from Humber Polytechnic's North Campus at Highway 27 in northern Etobicoke, using the college's former name of Humber College, to Finch West station on Line 1 Yonge–University, at Keele Street in North York.

Between the two terminals, there will be 16 on-street stops, all along Finch Avenue,[9] where tracks run in the middle of the street, segregated from traffic.

[12] From its western terminal, Humber College station, the line will run north in a trench along the west side of Highway 27 to its intersection with Finch Avenue, where the line will curve east in a short tunnel under the intersection and rise to street level along Finch Avenue.

[53][54] One block east of the Norfinch Oakdale stop, at York Gate Boulevard, there will be a wye junction to the line's maintenance and storage facility.

About 500 m (1,600 ft) east of the latter stop, opposite Romfield Lane, the line will descend into a tunnel under Keele Street to terminate inside Finch West station.

[60] Line 1 Yonge–University[66] TTC buses In January 2018, to avoid naming conflicts with existing TTC and GO stations in Toronto, a consultation process was initiated to select unique names for the stops at Jane, Kipling, Islington, and Weston; the initial suggestions were Jane and Finch, Mount Olive, Thistletown, and Emery Village, respectively.

[68] The line has been designed by Arup, DTAH and Perkins&Will – as part of the Mosaic Transit Group consortium.

This is to conform to crime prevention through environmental design (CPTED) standards to create a bright and safe environment for riders.

The turnback points from west to east are: Metrolinx has constructed a maintenance and storage facility (MSF) on a lot on the north side of Finch Avenue West between York Gate Boulevard and Norfinch Drive next to Monsignor Fraser College's Norfinch Campus.

The 100,000-square-metre (1,100,000 sq ft) site will include a maintenance building with an area of 10,000 square metres (110,000 sq ft),[12] open-air storage for up to 26 LRVs, a car wash facility, materials storage, an administration building and a traction power substation.

[76][73] In 2020, Metrolinx was criticized for proposing to sell off land in the Jane and Finch neighbourhood located in front of the MSF, contrary to initial promises to local community groups.

[77] A 32-metre-wide (105 ft) strip of land along Finch Avenue is currently being used as a construction staging area by Mosaic Transit Group.

In 2013, this plan was revived as an "unfunded future rapid transit project" in the City of Toronto's "Feeling Congested?"

With a forecast ridership of 6,600 in 2031 and a proposed line length of 6.3 kilometres (3.9 mi) along Finch Avenue West, the project scored "high" with a preliminary benefit–cost ratio of 0.36 to 0.65.