The line was approved unanimously by the City Council on December 19, 2012, after many years of debate on a rapid transit network for the city.
It represents the initial phase of the network and will be implemented through a 30-year Design-Build-Finance-Maintenance agreement with the Rideau Transit Group.
The Citadis Spirit light train will be used to provide passenger service.

On June 8, 2016, a sinkhole opened in the middle of Rideau Street near its intersection with Sussex Drive, 25 metres (82 ft) above the LRT tunnel construction, swallowing three lanes of the street and a parked van.
The collapse forced evacuation of the Rideau Centre and the closing of a number of local streets and businesses; no one was injured or killed, but the nearly-completed tunnel was flooded, submerging a roadheader.
Repairs were completed, and the city was cleared of any wrong-doing.

Testing of the line's rolling stock began in late 2016, and was planned to continue through most of the following year before the line was expected to achieve revenue service availability on May 24, 2018, followed by testing, acceptance, and opening of the line to the public.
When the May 2018 deadline could not be achieved, it was announced the line would open to the public in November 2018.
In September 2018, it was announced that the line would not open in November 2018 and would instead open in early 2019.
In March 2019, this was pushed back to sometime between April and June 2019.
In May 2019, the opening of the line was again delayed, until the third quarter of 2019, due to concerns about train operations.
Rideau Transit Group failed to complete testing and hand over the system by the revised deadline of August 16, 2019, the fourth time RTG had not met a deadline it had revised with the city.
OC Transpo announced on August 23, 2019, that the testing had been completed by RTG and the Confederation Line would open to the public on September 14, 2019.

On March 10, 2020, Ottawa City Council issued a notice of default to RTG, listing the flaws and problems with the line and its operation.
Among the cited issues were a shortage of trains during rush hour, a maintenance facility fire, inadequate heating of train operator cars, and vehicle parts coming loose, the latter causing damage to transponders.
The line was approved unanimously by the City Council on December 19, 2012, after many years of debate on a rapid transit network for the city. It represents the initial phase of the network and will be implemented through a 30-year Design-Build-Finance-Maintenance agreement with the Rideau Transit Group. The Citadis Spirit light train will be used to provide passenger service.
On June 8, 2016, a sinkhole opened in the middle of Rideau Street near its intersection with Sussex Drive, 25 metres (82 ft) above the LRT tunnel construction, swallowing three lanes of the street and a parked van. The collapse forced evacuation of the Rideau Centre and the closing of a number of local streets and businesses; no one was injured or killed, but the nearly-completed tunnel was flooded, submerging a roadheader. Repairs were completed, and the city was cleared of any wrong-doing.
Testing of the line's rolling stock began in late 2016, and was planned to continue through most of the following year before the line was expected to achieve revenue service availability on May 24, 2018, followed by testing, acceptance, and opening of the line to the public. When the May 2018 deadline could not be achieved, it was announced the line would open to the public in November 2018. In September 2018, it was announced that the line would not open in November 2018 and would instead open in early 2019. In March 2019, this was pushed back to sometime between April and June 2019. In May 2019, the opening of the line was again delayed, until the third quarter of 2019, due to concerns about train operations. Rideau Transit Group failed to complete testing and hand over the system by the revised deadline of August 16, 2019, the fourth time RTG had not met a deadline it had revised with the city. OC Transpo announced on August 23, 2019, that the testing had been completed by RTG and the Confederation Line would open to the public on September 14, 2019.
On March 10, 2020, Ottawa City Council issued a notice of default to RTG, listing the flaws and problems with the line and its operation. Among the cited issues were a shortage of trains during rush hour, a maintenance facility fire, inadequate heating of train operator cars, and vehicle parts coming loose, the latter causing damage to transponders.
Confederation Line