Markstay-Warren is a town in the Canadian province of Ontario, located in the Sudbury District.

Shortly after the completion of the transcontinental line of the CPR in 1885, a station and community was established at Rivière-Veuve, taking its name from the Veuve River that flows through this area.

In 1890, the Warren family of Toronto established a sawmill, slightly east of Rivière-Veuve, operating under the name Imperial Lumber Company.

The economic recession of the early 1990s hit the Warren area significantly hard as corporate restructuring and downsizing at Ontario Hydro and the OPP resulted in the closure of the Ontario Hydro office and reductions in staff at the OPP.

As a consequence, Warren's population suffered and many residents moved to larger centres such as Sudbury or North Bay.