| Mirza Hosein Khan Moshir od-Dowleh Sepahsalar | |
| Birth Date: | 1828 |
| Death Date: | 1881 |
| Death Place: | Mashhad, Persia |
| Order: | Grand Vizier of Persia (Iran) |
| Term Start: | 12 November 1871 |
| Term End: | September 1873 |
| Predecessor: | Mirza Yusuf Ashtiani |
| Successor: | Mirza Yusuf Ashtiani |
| Party: | Independent |
Mirza Hosein Khan Moshir od-Dowleh Sepahsalar (Persian: میرزا حسین خان مشیرالدوله سپه سالار) or simply Mirza Hosein Sepahsalar (Persian: میرزا حسین سپه سالار) (1828–1881) was the Grand Vizier (prime minister) of Iran (Persia) during the Qajar dynasty under King Naser al-Din Shah Qajar between 1871 and 1873.
After a successful career in the Iranian foreign service, serving in Tiflis, Hosein Khan was made ambassador to Istanbul during the great Ottoman reform period after 1856. He seems also to have been influenced by at least two reformist thinkers: Fatali Akhundov, whom he got to know well in Tiflis, and Mirza Malkam Khan, whom he met in Istanbul.
On becoming Grand vizier, Hosein Khan persuaded the Shah to grant a concession for railroad construction—the Reuter concession—and other commercial development projects to Baron de Reuter. Opposition from bureaucratic factions and clerical leaders, however, forced the Shah to dismiss his Grand Vizier and cancel the concession.