The suspected killer was detained just outside Moscow and was being sent for questioning by the Investigative Committee, a body similar to the FBI which oversees major criminal probes, a police spokesman told AFP.
Police and investigators identified the suspect as Orkhan Zeinalov, a 30-year-old native of Azerbaijan.
Investigative Committee spokesman Vladimir Markin said Zeinalov had lived in Russia for the past 10 years and made a living by driving a gypsy cab.
Thousands rioted in southern Moscow on Sunday over the killing several days earlier of 25-year-old local man Yegor Shcherbakov, who was stabbed to death in front of his girlfriend.
The killer fled the scene but images caught on surveillance cameras suggested he could have been from Central Asia or the Caucasus.
After a largely peaceful protest on Saturday, the rioting erupted Sunday when protesters attacked a wholesale vegetable market where they thought the suspected killer was hiding.
Authorities have decided to suspend the work of the market, the statement said, adding that investigators were considering to open a criminal probe against its management.
The police chief for the Western Biryulovo district where the riots took place was dismissed today, police said, while his counterpart in Moscow's southern district which includes Biryulyovo was also fired.
Muscovites have for years chafed at the huge numbers of Muslim migrants who travel to the Russian capital in search of work.
Despite a flare-up in inter-ethnic tensions, more than 100,000 Muslims gathered in Moscow to celebrate Kurban Bairam (Eid el-Adha), a major Islamic holiday known as the Festival of Sacrifice. Police reported no incidents.
