CDPQ has bought a 25% stake in the project for a fee of £644 million (EUR 781 million). Dong will continue to own a holding of the same size.
The Danish energy firm said the sale had nothing to do with Thursday's approval of Goldman Sachs' buy-in to Dong, adding that the move it part of a financial action plan set out in February 2013.
"Farm down of our ownership shares in wind projects is a central part of our business model and our strategy is to continuously enter into partnership agreements with industrial and financial partners to extract part of the value creation from our projects," said Samuel Leupold, executive vice president of Dong wind power.
It said the sale is aimed at releasing equity to reduce its debts.
E.on continues to hold a 30% share in the development, with Masdar claiming the remaining 20%. Dong will continue to provide operations and maintenance services to London Array.
A possible deal for the sale of a 24% stake in the project to CPDQ was raised in February. Dong refused to comment at the time.
CPDQ manages the pension contributions of public-sector workers in the Canadian province of Canada. It handles total funds of around CAD 176 billion ($157 billion).
London Array, produced 2TWh of electricity in 2013, according to the project's management company.
The first power was generated in October 2012, several months behind schedule and the project was fully operational in April 2013.