6 October 2022: Senator Benjamin E. "Ben" Sasse (Republican) stated he will resign by the end of 2022 to become President of the University of Florida. Governor J. Peter "Pete" Ricketts (Republican) will then appoint a replacement to fill the seat through January 2025. A special election will be called in 2024 to fill the final 2 years of the term which ends in January 2027.

10 November 2022: Florida's Board of Governors names Senator Sasse as president-elect of the University of Florida.

5 December 2022: Senator Sasse, who was first elected in 2014 and re-elected in 2020, submits his resignation effective 8 January 2023. Governor-elect Jim Pillen (Republican) will begin receiving applications and evaluating replacement candidates. The deadline for applications is 23 December 2022.

12 January 2023: Governor Jim Pillen (Republican) appoints Pete Ricketts (Republican) to fill the vacant seat. He was sworn on 23 January 2023.

5 November 2024: Senator Peter "Pete" Ricketts (Republican) won the special election.

25 February 2022: Senator Inhofe, 87, announced his retirement effective in January 2023. Oklahoma requires a special election when an incumbent announces retirement before 1 March. The special primary election is 28 June, runoff 23 August, and general election on 8 November 2022.
Senator James M. "Jim" Inhofe (Republican) was first elected to fill out the term in a Special Election in 1994 [held to fill the impending vacancy caused by the resignation of Senator David L. Boren (Democrat): effective, 15 November 1994 but announced before the 1994 Oklahoma state/local Primary in August 1994, allowing for this Special Election to take place]; elected to a full term: 1996; re-elected: 2002, 2008, 2014, 2020.
8 November 2022: Member of Congress Markwayne Mullin (Republican, CD 2) won the Senatorial Special Election with 62% of the vote. Member of Congress Mullin will fill the seat of Senator James M. "Jim" Inhofe (Republican) when Senator Inhofe retires in January 2023. The term ends in 2027.
Senator Inhofe resigned on 2 January 2023.
Senator Markwayne Mullin took the Oath on 3 January 2023.

Senator Markwayne Mullin was first elected to fill out the term in a Special Election on 8 November 2022 [held to fill the impending vacancy caused by the resignation of Senator James M. "Jim" Inhofe (Republican) on 3 January 2023 but announced before the 2022 Oklahoma state/local Primary in June 2022, allowing for this Special Election to take place].
5 March 2026: Senator Markwayne Mullin was nominated for Secretary of Homeland Security by President Donald Trump. If Senator Mullin is confirmed and the Senate Seat is vacated, Oklahoma Governor J. Kevin Stitt (Republican) will appoint a replacement who will serve until the next regularly scheduled election. The replacement must pledge not run for the seat in the next election-- this provision may not be enforceable.
12 March 2026: Governor J. Kevin Stitt (Republican) stated he would not announce a replacement until after Senator Mullin is confirmed.
Senator Markwayne Mullin's confirmation hearing is scheduled for 18 March 2026.
Media reports state that Governor J. Kevin Stitt (Republican) will appoint Alan S. Armstrong (Republican) to fill the remainder of the term which ends in January 2027.
23 March 2026: Senator Markwayne Mullin is confirmed as Secretary of Homeland Security by the U.S. Senate 54-45.
24 March 2026: Senator Markwayne Mullin is sworn as Secretary of Homeland Security.
24 March 2026: Governor J. Kevin Stitt (Republican) appoints Alan S. Armstrong (Republican) to fill the remainder of the term which ends in January 2027. Senator Armstrong was sworn shorty thereafter.