The Topeka Democrat also is the Legislature's longest-serving member, having been elected to the House in 1976, then to the Senate in 1992.
There was some speculation that Hensley would face a challenge. But no one stepped forward.
Democrats went into this year's election holding 10 of the Senate's 40 seats, and they suffered a net loss of one. That means Republicans will have a 31-9 majority when the 2009 Legislature convenes Jan. 12.