The Canadian newcomers, who overcame Halifax amateur club Siddal 14-6 in the third round last Saturday, will face the former Super League club in the capital on the weekend of March 18-19.
The Broncos were cup finalists in 1999 and, although they were relegated from Super League three years ago, they are currently third in the Kingstone Press Championship after winning three of their opening four matches.
Toronto will also be in London on Saturday to kick off their League 1 campaign against the Skolars.
The highlight of the fourth-round draw, which was made by former cup winner and Great Britain captain Paul Sculthorpe on board HMS Bulwark in Plymouth was the clash between Bradford and Featherstone, a repeat of the 1973 final which was played at Wembley.
There are other all-Championship ties at Hull KR, who host Sheffield Eagles, and Toulouse, who meet Batley, while St Helens amateurs Haydock, the only community club level in the draw, face an away tie against Oldham.
The BBC say a total of 41,936 viewers tuned in to watch Toronto's game at Siddal and they will stream a fourth-round tie live on their website.
Four of the Super League clubs will join the competition at the following round stage while the remaining eight enter in round six.
Fourth-round draw: Hull KR v Sheffield Eagles, Swinton v London Skolars, Bradford v Featherstone, Toulouse v Batley, Oldham v Haydock, University of Gloucestershire v Doncaster, Whitehaven v Oxford, York v Rochdale, London Broncos v Toronto, Dewsbury v Newcastle, Halifax v Hunslet, Barrow v Keighley.
Ties to be played on the weekend of March 18-19.
