Laureate of the National Chamber Music Competition (1983).
As a soloist and as part of various collectives, he performed in the best concert halls of Ukraine, Austria, Denmark, Spain, Italy, the USA and other countries.
Violin class teacher at the National Music Academy of Ukraine from 1994 to 2003.
From 2011 to 2016, he was a teacher at the Kyiv Glier Institute of Music.
The musician collaborated with outstanding performers: N. Matvienko, A. Bazhenov, V. Buimister, B. Kotorovych, V. Matyukhin, A. Vinokurov, G. Nuzha, V. Samofalov, P. Polukhin and others.
Oleksiy Alekseev participated in the world premieres of works by Y.Vereshchagin, L.Dychko,  A.Zagaykevich, I.Karabyts, O.Kolodub, O.Kiva, V.Runchak, Y.Stankovych, V.Silvestrov, K.Tsepkolenko, I.Shcherbakova and others.