Colorado's 31st Senate district is one of 35 districts in the Colorado Senate.

It has been represented by Democrat Matthew Ball since 2025, following the resignation of fellow Democrat Chris Hansen.

[3] District 31 is based in the central and southeastern neighborhoods of Denver, including Capitol Hill; the district also includes the Arapahoe County exclaves of Glendale and Holly Hills.

[5] At 23 square miles, it is the smallest Senate district in the state.

[1] Colorado state senators are elected to staggered four-year terms; under normal circumstances, the 31st district holds elections in presidential years.