Has one older brother, Igor Marchenko, a manager and former ice skater who took part in the 1998 Winter Olympics.

He then attempted to qualify for his first ATP World Tour event in Marseille, but lost in the first round of qualification to Jérémy Chardy.

In May, Marchenko reached the semi-final of the Türk Telecom İzmir Cup Challenger in Turkey before losing to eventual champion Gilles Müller.

Marchenko then closed out his year with solid performances in two Ukrainian Challengers, reaching the Quarterfinals and Semifinals in each, respectively.

In March, Marchenko played his first live rubber in Davis Cup after being selected as second singles man for the Ukrainian team in the tie versus Great Britain.

Marchenko defeated Josh Goodall, Britain's first singles man in the absence of Andy Murray in straight sets.

Marchenko played his first ATP World Tour match in Marseille after winning 3 rounds of qualification.

Marchenko attempted to qualify for the first time into the main draw of a Grand Slam at the 2009 US Open, but lost to Marco Chiudinelli in the final round of qualification.

In October, Marchenko won 6 matches in a row before losing to countryman Sergiy Stakhovsky in the semi-final of the Mons Challenger in Belgium.

After winning three rounds of qualification matches, Marchenko reached his second ever ATP World Tour main draw.

At the 2009 edition of the Presidents Cup in Astana, Kazakhstan, after defeating Björn Phau in the semifinals of the indoor hardcourt tournament, Marchenko bowed out to Andrey Golubev.

Marchenko then travelled to Zagreb in February 2010 and made it to the quarterfinals after defeating Simone Bolelli and Ivan Dodig before losing to Jürgen Melzer.

After beating Ruben Bemelmans and Olivier Rochus he faced top-10 seed Jo-Wilfried Tsonga in the quarterfinals.

In October he earned 90 ATP ranking points at the 2010 St. Petersburg Open after reaching the semifinals, losing to eventual champion Mikhail Kukushkin.

[4] In Bogota at the 2013 Claro Open Colombia, Marchenko played a first round hard court match against Matteo Viola and lost 3–6, 6–2, 0–6.

At the 2016 Qatar ExxonMobil Open he managed to defeat three top 50 players, including a first round win against the defending champion David Ferrer, much against all expectations.

Marchenko then lost in four sets to third seed Stan Wawrinka in the fourth round, his best showing at a Grand Slam in his career.

[6] At the 2023 Hamburg Ladies & Gents Cup he defeated top seed Dennis Novak to lift his tenth Challenger title.