[1] He is the eldest of two children born to Yelena, a real estate agent, and Gennadiy, a natural gas and oil marketer.

[3] Mitrofanov began learning to skate in 2001 at the age of four after doctors encouraged his parents to enter him into sports as a way to improve the weak immune system he had been born with.

[4] Making their international debut, the pair placed 12th at an ISU Junior Grand Prix (JGP) event in the Czech Republic in September 2016.

In January, they won the junior pairs' title at the 2018 U.S. Championships; they ranked first in both segments and outscored the silver medalists by 17.74 points.

In March, the pair placed 5th (6th in the short program, 4th in the free skate) at the 2018 World Junior Championships in Sofia, Bulgaria.

They were invited to two Grand Prix events, the 2018 NHK Trophy and 2018 Internationaux de France, where they placed seventh and sixth, respectively.

[6] With the COVID-19 pandemic affecting international travel, Lu/Mitrofanov were assigned to attend the 2020 Skate America, the Grand Prix having been arranged primarily based on training location.

[8] Coming fourth in the free skate, their lead from the short program was nevertheless enough to remain in third place overall, winning the bronze medal.

[11] After beginning the season with some minor America competitions, Lu/Mitrofanov competed on the Grand Prix at the 2021 NHK Trophy, finishing in fifth place.

[15] As a result of their placement, they were assigned to compete at the 2022 Four Continents Championships in Tallinn, and named second alternates to the American Olympic team.