Broadly speaking, the Fraser Valley is that section of the Fraser River basin in southwestern British Columbia downstream of the Fraser Canyon. After descending through the treacherous rapids of the Fraser Canyon, the Fraser River emerges almost at sea level at Yale, over 100 km inland. The river passes through some of the most fertile agricultural land in British Columbia--as well as the heart of the Greater Vancouver region--on its way through the valley to its mouth at Georgia Strait. During the last Ice Age, the area that would become the Fraser Valley was covered by a sheet of ice, walled in by the surrounding mountains. As the ice receded, land that had been covered by glaciers became covered by water instead, then slowly rose above the water, forming the basin that exists today.

This section of the Fraser River--called Stolo by the Coast Salish First Nations--was a vital lifeline before European contact, and has been an important transportation corridor since then as well. In the 19th century, steamboats plied the waters between Georgia Strait and Yale, and were especially busy during the gold rush of the 1850s and 60s. Boats continued to provide a vital link in the valley as the gold rush tapered off and Europeans began farming. Eventually, roads and railways were built, fueled by and in turn fuelling population growth. Today, the most important transportation links through the region are the Canadian Pacific Railway and Canadian National Railway transcontinental main lines, and the Trans-Canada Highway.

Today, the Fraser Valley is a mishmash of land uses, ranging from the urban and industrial centres of Vancouver, Surrey, and Abbotsford through golf courses and parks to dairy farms and market gardens. Agricultural land in the valley--protected by the Agricultural Land Reserve--is intensively farmed: the Fraser Valley brings in over half of British Columbia's annual agricultural revenue, even though it makes up a tiny percentage of the province's total land area. As the valley population grows and traffic increases, air pollution becomes an increasingly important issue, and various controversies have erupted over the years on the question of whether or not air pollution is a problem, and if it is a problem, what should be done about it.

In colloquial usage, "Fraser Valley" refers only to that part of the valley beyond the continuously built-up urban area around Vancouver; in other words, "the Valley" in Vancouver means much the same thing as it does in Los Angeles (something beyond the pale, from a city-dweller's point of view). Fraser Valley can also refer to the Fraser Valley Regional District, which consists of the incorporated municipalities in the eastern two-thirds of the valley.