Oleksiyenko was awarded the title of Grandmaster by FIDE in 2005.

In 2014 Oleksiyenko tied for first with Baadur Jobava and Sergey Fedorchuk, placing third on tiebreak, in the David Bronstein Memorial in Minsk.

[3] In 2015, he won the Karen Asrian Memorial in Jermuk with a score of 7/9 points, edging out Anton Korobov and Samvel Ter-Sahakyan on tiebreaks.

[4] In 2016, Oleksiyenko won the Ukrainian Chess Championship.

[5][6] In 2008 Oleksiyenko graduated from the faculty of mechanics and mathematics at Ivan Franko Lviv National University.