was a Bakumatsu period daimyà  under the Edo period Tokugawa shogunate of Japan. He was the 7th daimyà  of Itoigawa Domain in Echigo Province and later the 17th (and final) daimyà  of Fukui Domain in Echizen Province.
Mochiaki was the fourth son of Matsudaira Naoharu of Itoigawa. He was received in formal audience by Shà Âgun Tokugawa Ieyoshi in 1852. His childhood name was Yuanosuke (éÂÂä¹Âå©). He underwent his genpuku ceremony in 1853, becoming Matsudaira Naokiyo (ç´å»Â). On the retirement of his father in 1857, he became daimyà  of Itoigawa. At that time, his courtesy title was Hyà «ga-no-kami and his court rank was Junior Fifth Rank, Upper Grade.
In 1858, Matsudaira Yoshinaga (better known as Matsudaira Shungaku) was forced into retirement during the Ansei Purge, and Naokiyo was transferred to Fukui Domain and was adopted as Yoshinaga's successor. His courtesy title became Echizen-no-kami, and also Sakon'e-no-chà «jà Â, and his court rank was increased to Junior Fourth Rank, Upper Grade. Also, Shà Âgun Tokugawa Iemochi granted him a kanji from his name, which then became Matsudaira Mochiaki. Uni 1864, his court rank became Senior Fourth Rank, Lower Grade.
However, he was mostly a figurehead within Fukui Domain, as the retired Matsudaira Yoshinaga continued to exert much influence, and all of the powerful retainers of the domain, including Yuri Kimimasa, Yokoi Shà Ânan, etc. continued to be loyal to their former lord.
During the First Chà Âshà « expedition, he served as deputy commander under the overall command of Tokugawa Yoshikatsu.
In June 1869, he defected to the side of the new Meiji government and was appointed imperial governor of Fukui, a post which he held to the abolition of the han system in 1871. In 1884, he became a Count (hakushaku) in the kazoku peerage system. He was awarded the Fourth class of the Order of the Rising Sun in 1885. In 1889, he inherited the title of Marquis (koshaku) from his adopted father.
He died in 1890. His son, Matsudaira Yasutaka (1867âÂÂ1930) served as a member of the House of Peers of the Diet of Japan and was author of a number of works on agricultural science, having studied for several years in England.