According to the United States Census Bureau, the city has a total area of 38.06 square miles (98.57 km ), of which 37.77 square miles (97.82 km ) is land and 0.29 square miles (0.75 km ) is water. Water features in the city include Shelley Lake, a small lake which is fed by the Saltese Creek.

The City of Spokane Valley lies along the banks of the Spokane River as it flows from its source in Lake Coeur d'Alene on its way to the Columbia River at the Franklin D. Roosevelt Lake reservoir. The city lies along both banks of the river, but most of the city lies to the south of the river. To the south of the valley in which the city sits is the southern extent of the Selkirk Mountains, which are most prominent in the area east of Coeur d'Alene. The valley is within the Northern Rockies Level III ecoregion. The valley exhibits signs of the prehistoric geologic events that shaped the area and region such as the Missoula Floods which ended 12,000 to 15,000 years ago. The Spokane valley was gouged out by repeated failures in the ice dam that held Glacial Lake Missoula.

The city limits are roughly defined to the west and southwest by Havana Street and the Dishman Hills Conservation Area; to the north by Felts Field, the City of Millwood, the Spokane River, and a few minor roads north of the river; to the east by Barker Road; and to the south by the small hills which divide the city from the Palouse region.

The city of Spokane Valley is part of the Spokane–Coeur d'Alene Combined Statistical Area (CSA) and lies between the two anchor cities, directly east of Spokane and to the west of Coeur d'Alene. The city is also part of the wider Inland Northwest region, consisting of eastern Washington, northern Idaho, northwestern Montana, and northeastern Oregon.
Prior to World War II, Spokane Valley had been a predominantly rural area, a productive site for farms and orchards since it was first irrigated in 1895. In 1940, the population of the valley was 10,000. During World War II, with increased industrial activity in the central business district, particularly the railroads, new migrants to the Spokane area began to settle, shop, and do business in outlying areas where it was more quiet and less crowded and blighted. In 1960 the population of the valley was about 45,000 and by 1970 it had become a suburb of 60,000 residents. The City of Spokane Valley incorporated in 2003, centered around the historic communities of Opportunity, Dishman, and Veradale and including the communities of Greenacres, Trentwood, Yardley, and Chester, forging together an assemblage of small townships, mercantile hubs, and unincorporated communities. Because the City of Spokane Valley shares its name with the unincorporated area it was carved from, the term "Spokane Valley" is often used in reference to an area greater than that defined by the city limits.
Spokane Valley experiences a temperate climate (Köppen Csa), with a warm summer and rainy winter. Precipitation averages just over 16 inches (410 mm) annually, with December averaging the most precipitation with 3.5 inches (89 mm) and July the least with 0.6 inches (15 mm). July is the hottest month of the year, with an average temperature of 73 °F (23 °C) and January is the coldest, with an average temperature of 28.3 °F (−2.1 °C).

Spokane Valley first appeared as a city in the 2010 U.S. Census after being incorporated in 2003 from all or the predominant parts of the deleted Dishman, Green Acres, Opportunity, Trentwood, and Veradale CDPs and additional area.
As of the 2020 census, there were 102,976 people, 45,163 households in the city.
As of the 2010 census, there were 89,755 people, 36,558 households, and 23,119 families residing in the city. The population density was 2,376.4 inhabitants per square mile (917.5/km ). There were 38,851 housing units at an average density of 1,028.6 per square mile (397.1/km ). The racial makeup of the city was 90.9% White, 1.1% African American, 1.2% Native American, 1.7% Asian, 0.3% Pacific Islander, 1.4% from other races, and 3.3% from two or more races. Hispanic or Latino of any race were 4.6% of the population.

There were 36,558 households, of which 31.6% had children under the age of 18 living with them, 45.6% were married couples living together, 12.2% had a female householder with no husband present, 5.4% had a male householder with no wife present, and 36.8% were non-families. 29.0% of all households were made up of individuals, and 11.2% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 2.99.

The median age in the city was 37.3 years. 24% of residents were under the age of 18; 9.5% were between the ages of 18 and 24; 26.1% were from 25 to 44; 26.4% were from 45 to 64; and 14.1% were 65 years of age or older. The gender makeup of the city was 48.9% male and 51.1% female.

The Spokane Islamic Center in Spokane Valley became the first mosque in the Spokane area in 2009. A messianic Jewish synagogue and two Sikh temples are also located in the city.

The greater valley area is also home to the 59th temple of The Church of Jesus Christ of Latter-day Saints, dedicated in 1999, which administers 15 regions across eastern Washington, northern Idaho, and northwestern Montana.
An organization that is dedicated to cultivating the arts in the city is the Spokane Valley Arts Council, an independent non-profit organization founded in 2004. The council maintains an exhibit of local artists in the CenterPlace Regional Event Center foyer, and commissions sculptures and monuments for community parks and buildings, as well as sponsors an artist showcase auction and fundraiser each October. The exhibits are rotated every three months.

In the theatre arts, the professional not-for-profit Spokane Valley Summer Theatre provides a season of live theater in the Central Valley Performing Arts Center located in Central Valley High School.
The Spokane Valley Heritage Museum opened in 2005 and is located in the historic Spanish mission revivalist-style Opportunity Township Hall. The museum's goal is to collect, preserve and exhibit the history and culture of the Spokane Valley and the museum houses archives of old newspapers and records, photographs, as well as exhibits that feature stories about the Native Americans that historically inhabited the valley, apple orchards and industry in the valley, and exhibits that recount the city's early history with aircraft and flight.
On the Friday after Labor Day, the Spokane County Fair and Expo Center hosts the ten-day Spokane County Interstate Fair. Events and activities at the fair revolve around traditional county fair activities such as carnival games and rides, food, a rodeo, and a livestock show accompanied by live music.

The Spokane County Fair and Expo Center is home to dozens of various events throughout the year; it is situated on 97 acres (0.39 km ), with over 140,000 square feet (13,000 m ) of exhibition space, livestock facilities, indoor and outdoor arenas, lawns, and parking.
Valleyfest is an annual three day festival held every September at Mirabeau Point Park, the adjacent CenterPlace Regional Event Center, and Plantes Ferry Park and Sports Complex. Festivities include the Hearts of Gold parade down Sprague Avenue, "Fishing at the Falls", a classic car show, and a 5K or 10K run and duathlon that starts and ends at Plantes Ferry Park. The event features live music and hosts various other activities at the CenterPlace Regional Event Center.
The Inland Northwest Craft Beer Festival (formerly the Spokane Oktoberfest) is a two-day beer festival hosted by the Washington Beer Commission annually in September at Avista Stadium. The festival showcases the offerings of local and Washington state breweries and sometimes breweries in other western states. The festival features live music and food truck vendors for attendees; one day of the festival caters to family friendly activities as well and features a bouncy house.