The 57-year-old Mustafoev is a former prosecutor-general, former Constitutional Court chairman, and former Central Election Commission chairman.
He had been in charge of the Justice Ministry since early 2005. Who will replace him is still unclear.
Also today, the Senate appointed First Deputy Foreign Minister Isan Mustafoev Uzbekistan's new ambassador to Brussels.
The UzMetronom.net independent news website describes Isan Mustafoev as a carrer intelligence officer.
Finally, the Senate approved a draft ratification bill on the resumption of Uzbekistan's membership into the Collective Security Treaty Organization (CSTO).
State-controlled media says the decision marks Tashkent's formal re-entry into the Russian-led regional grouping that also comprises Armenia, Belarus, Kazakhstan, Kyrgyzstan, and Tajikistan.
Uzbekistan decided to rejoin the CSTO at an informal CIS sumit in Sochi in August.
It had stopped its membership into the organization in 1998.
(UzA, UzReport, press-uz.report, uzmetronom.net, minjust.uz)