The highway was originally proposed on June 8, 1925 from Brenham east through
Navasota and
Conroe to
Cleveland, roughly paralleling a local railroad line. By 1926, the section from Brenham to Navasota was transferred to
SH 90. On April 6, 1932, a proposed extension east to
Moss Hill was designated. On July 12, 1933, a new section of SH 105 was under construction, being built westward from Beaumont to Moss Hill, replacing
SH 133. On March 19, 1935, it was shifted north through Rye. On July 15, 1935, all of
SH 105 east of Cleveland was cancelled (as it had not been built yet). On February 11, 1937, the section from Moss Hill to Beaumont was restored (but not Cleveland to Rye, so a gap was created). On February 25, 1937,
SH 105 Loop was designated through Conroe. On June 21, 1938, the Cleveland-Neville's Ferry Road from Cleveland to Rye had its routing approved, and construction started on it. On March 18, 1947,
SH 105 was routed on the Cleveland-Neville's Ferry Road, closing the gap. Construction was sporadic, with the section between Conroe and Beaumont not completed until the 1960s. On March 26, 1962, the section of SH 105 from Moss Hill and on a line equidistant between Batson and Saratoga to FM 770 was cancelled, creating a gap. On February 28, 1973, the section of SH 90 from Navasota to Brenham was transferred back to SH 105 and the section of SH 105 from SH 6 west to Loop 508 (now Business SH 6) was transferred to Spur 515. The current route was set on December 21, 1984 with the highway replacing
FM 162 and shortening the route from
Cleveland to Beaumont. The old route became part of
FM 787. One portion of FM 162 was originally designated as
FM 1935. On August 25, 2005, a new routing around Cleveland was approved for construction, while the section through Cleveland was designated as a business route of 105: 105-T. Construction has been completed. ==Business routes==