State Highway 105, or SH 105, is a state highway in the U.S. state of Texas that runs from Brenham to the outskirts of Beaumont. The route was originally proposed in 1933 and took its current routing in 1984.

SH 105 begins as a pair of one-way roads at an intersection with Business U.S. Route 290 in downtown Brenham. It then progresses northeast out of Brenham through mainly farming lands. It passes near Washington-on-the-Brazos, Texas, which is the birthplace of Texas as the location of the signing of the Texas Declaration of Independence. It then crosses the Brazos River before passing through Navasota. The route briefly joins SH 6 before proceeding east again. It passes near Lake Conroe before entering the city of Conroe and an intersection with Interstate 45. The route continues east, passing through the very southern edge of Sam Houston National Forest before reaching Cleveland and an intersection with Interstate 69. The route continues east out of Cleveland, briefly coinciding with SH 321, passing through a large section of East Texas Piney Woods, before reaching its eastern terminus at U.S. Routes 69, 96, and 287 on the far northern edge of Beaumont.

The highway was originally proposed in 1926 from Navasota east through Conroe to Cleveland, roughly paralleling a local railroad line. By 1933 the route was completed as an earthen road, with a proposed extension east to Moss Hill. By 1939, a new section of SH 105 was under construction, being built westward from Beaumont, replacing SH 133. Construction was sporadic, with the section between Conroe and Beaumont not completed until the 1960s. In 1973, SH 105 was extended southwest into Brenham, replacing a section of SH 90. The current route was set in 1984 with the highway replacing FM 162 and shortening the route from Cleveland to Beaumont. In 2005, a new routing around Cleveland was approved for construction, while the section through Cleveland will be designated as a business route of 105: 105-T.

SH 105 has one business route.

Business State Highway 105-T is a future Business Loop that will run on the current routing of SH 105 through Cleveland in central Texas. The road was designated in 2005, but was awaiting completion of the bypass routing of the main highway south of Cleveland as of 2008.