The Senate is the upper chamber of the West Virginia Legislature. The state constitution requires that a senator be at least 25 years old, a resident of the district for at least one year prior to election, and a citizen of the state for at least five years.

Under West Virginia's original 1863 constitution, senators served two-year terms, but since a new constitution was adopted in 1872, senators have served four-year terms. The Senate always has had two members from each district, but the number of senatorial districts has increased over the years with a corresponding increase in the number of senators. In the beginning, there were nine districts and a total of 18 senators. In 1872, the numbers increased to 12 districts and 24 senators. By 1903, there were 15 districts and 30 senators. That remained unchanged until 1939, when the state was divided into 16 districts with 32 senators.

The most recent change in the size of the Senate occurred in 1964, when lawmakers decided to create a 17th district in Kanawha County by overlaying in onto the 8th District, which already covered the county, and the total number of senators became 34. After that, four senators from the geographically identical districts represented Kanawha County residents until the county's population loss in the 2010 Census prevented that system from continuing. After redistricting in 2011, the 8th and 17th districts became geographically distinct for the 2012 elections.

Senatorial terms are staggered so that one member from each district is elected every two years. Thus, half of the Senate is elected at a time, and the entire Senate is up for election within a four-year period.

Twice, after the elections of 1910 and 1912, the Senate has been split evenly between Republicans and Democrats with 15 members each. That caused a notable deadlock in 1911, when the selection of members of the U.S. Senate was still in the hands of state legislators rather than the voters. Senator Nathan Scott's term had expired and Senator Stephen Elkins died in office that January, so the Legislature had the rare opportunity to choose both of West Virginia's U.S. senators. The Democrats controlled the House of Delegates, but a Republican, William Glasscock, was governor. In an attempt to prevent the state from sending two Democrats to the U.S. Senate to replace Scott and Elkins, Republican state senators decided to deny the West Virginia Senate a quorum; Glasscock would be unable to make the appointments if the Legislature failed to act. The Republican senators initially holed up in the governor's office, but to avoid the possibility that Democrats would use state law to compel them to appear in the Senate chamber, they fled to Cincinnati. They eventually agreed to a compromise that allowed the Democrats to choose the new U.S. senators while Republican Henry Hatfield became state Senate president.

The Senate is equal to the House of Delegates in passing resolutions and bills, including the state budget. But the Senate has the sole authority to confirm or reject appointments made by the governor. In the impeachment process, it is the Senate's duty to hold a trial for a state official impeached by the House of Delegates. Twice the Senate sat as a court of impeachment; it removed Treasurer John Burdett from office on January 29, 1876, and it censured Supreme Court Justice Beth Walker on October 2, 2018. Two other officials were impeached in the House, in 1926 and 1989, but both chose to resign rather than face trial in the Senate.

The Senate president is first in line to fill a vacancy in the governor's office. Daniel D.T. Farnsworth served as West Virginia's second governor for one week in 1869 after Governor Arthur Boreman resigned to become a U.S. senator. After the disputed election of 1888, Senate President Robert Carr tried to assert the right to become governor. He failed when incumbent Governor E.W. Wilson was allowed to remain in office until the dispute was resolved more than a year later.

In 2010, Senate President Earl Ray Tomblin became acting governor after Governor Joe Manchin resigned the governor’s office to succeed the late Robert Byrd in the U.S. Senate. Tomblin was elected governor in 2011 to finish the rest of Manchin's term. He was reelected to a full term as governor in 2012.

Some of the darkest days of the Senate occurred in the 1980s, when the political careers of two successive presidents, Dan Tonkovich and Larry Tucker, and Senate Majority Leader Si Boettner were cut short by guilty pleas in a series of influence-peddling cases. Tonkovich and Tucker both pleaded guilty to extortion. Boettner pleaded guilty to tax evasion.

The longest-serving Senate president was Tomblin, who served in the position for almost 17 years, more than twice as long as any previous Senate president. He served almost one year as both Senate president and governor before resigning from the Senate on November 13, 2011, to assume the term of governor. However, during that year, Tomblin concentrated on his duties as governor and made only a few appearances in the Senate. That situation led to a power struggle in the Senate in 2011, when Senator Jeff Kessler, a Marshall County Democrat who had been chairman of the Judiciary Committee, prevailed in being elected to the newly created position of acting president of the Senate while Tomblin was acting as governor. One day after Tomblin’s inauguration for his elected term as governor, the Senate elected Kessler as president, and the position of acting president of the Senate was no longer needed.

In the 2012 election, Republicans gained three seats for a total of nine in the Senate, but Democrats remained firmly in control with the other 25 seats. That changed in the dramatic election of 2014, when 18 Republicans and 16 Democrats were elected to the Senate. After the 2020 election, Republicans held 23 seats in the Senate. As of 2024, Republicans hold the Senate by a margin of 31 to 3.