Nikolchenko made her World Cup Challenge debut at the 2018 Guadalajara World Challenge Cup, where she finished 5th in the all-around, 4th in hoop and 4th in ribbon. She also took part in the Holon Grand Prix, where she also placed 5th in all-around and won the silver medal for hoop and clubs. At the 2018 European Championships, Nikolchenko finished 11th. At the 2018 Minsk World Challenge Cup, she placed 5th in the all-around and qualified to three finals. She won bronze with hoop, finished 4th in ribbon and 6th in ball. At the 2018 Rhythmic Gymnastics World Championships, she placed 5th in the clubs final, 7th in ribbon, 8th in hoop and 4th in the all-around. Her team finished 5th for the team competition. Nikolchenko finished her 2018 season at the Grand Prix Final in Marbella, where she won the all-around gold. She also won gold in clubs, gold in ribbon and silver in ball.