The name is from the Algonquin Temikami or Temikaming, meaning "deep body of water with rapid winds” There are 30 species of fish in Lake Timiskaming, the best known are northern pike, sturgeon, lake trout, walleye, smallmouth bass, bullhead, carp, burbot, perch, and whitefish.

It is also the remnants of a huge basin called Lake Ojibway, which existed about 9,500 years ago.

One of Canada's greatest boating tragedies occurred when twelve boys and a staff member of Ted Byfield's St John's School of Claremont died of drowning and hypothermia on a canoe trip on 11 June 1978 on the lake.

It is the northern extension of the Ottawa-Bonnechere Graben, which is part of the Saint Lawrence rift system.

There are numerous faults in the area and has produced cliffs such as Devil's Rock, just 5 km (3 mi) south of Haileybury and is dated to be 2.2 billion years old.