Following the death of his father, Belknap became vice-president of his hardware company, a position which he held for the rest of his life.

In addition to his business career, Belknap served in the Kentucky State Guard, eventually rising to the rank of lieutenant colonel.

He campaigned on his business experience and opposition to policies of the incumbent governor, J. C. W. Beckham, whom Belknap lost the election to.

In 1910, he died of pernicious anemia, a condition which is believed to have been worsened by a mysterious ailment he contracted while in Puerto Rico.

[2] He was mustered into federal service on May 13, 1898, and departed the same day, spending several weeks at Lexington, Kentucky, before arriving at Newport News, Virginia, on July 28, 1898.

[4] On August 1, general Frederick Dent Grant ordered six companies under Belknap to board the USRC Hudson bound for Puerto Rico.

[4] Arriving at Ponce on August 11, the men were forwarded to Mayagüez,[4] and were ordered to follow the 11th Infantry Regiment inland as soon as transport could be secured.

[9] Belknap touted his business management experience, contrasting it with charges that his opponent, incumbent governor J. C. W. Beckham, had mismanaged the state's eleemosynary institutions.

[7] The New York Times reported, "Col. Morris B. Belknap, the Republican nominee for Governor of Kentucky, is an athlete as well as a politician and a millionaire businessman.

[10] Election day was a rowdy one throughout the state, and a judge supporting Belknap was shot by a sheriff at a polling place in Louisville.

[11] Victory went to Belknap's opponent; Beckham won the election 229,014 to 202,764, marking the first time in sixteen years that the Democrats had gained a majority of the votes cast.

[13][page needed] In July 1908, he traveled to Europe in order to improve his health, but after his return in October, his condition worsened again.