Rather than seeking spectacular play, he prefers balanced positions where he can gradually impose his deep understanding of the game.

Kirill Alekseenko learned to play chess at the age of four thanks to his grandfather and quickly stood out in youth competitions. In 2007, he became the European Under-10 Champion, and four years later he won the World Under-14 Championship, confirming his status as one of Russia's brightest chess prospects. He earned the Grandmaster title in 2015 and established himself on the international stage by winning the prestigious Chigorin Memorial three years in a row (2015, 2016, and 2017), as well as claiming victory at the 2018 Rilton Cup.

The year 2019 marked the turning point of his career. He surpassed the 2700 Elo rating barrier, delivered an outstanding performance at the FIDE World Cup, and finished third at the Isle of Man Grand Swiss. Thanks to that result, he received a wild card invitation to compete in the 2020–2021 Candidates Tournament, the event that determines the challenger for the World Chess Championship. In his debut appearance, he faced some of the world's strongest players and finished seventh with 5.5 points out of 14, an impressive achievement for a 22-year-old making his first appearance in the event.

Alekseenko is known for his solid and strategic playing style, built on outstanding opening preparation, strong defensive skills, and an excellent understanding of endgames. Rather than seeking spectacular play, he prefers balanced positions where he can gradually impose his deep understanding of the game. Following Russia's invasion of Ukraine in 2022, he was among the Russian grandmasters who signed a public letter opposing the war, and he later began competing under the Austrian Chess Federation. Today, he maintains an Elo rating of around 2650 and continues to compete regularly in top-level international tournaments, establishing himself as one of the most reliable grandmasters of his generation.