[4] Her horse is named as Chopin VA.[5][6] In 2023, Karlsson was banned from competition from the FEI for failing to attend drug testing.

[7] Mathilda was born in Kandy, Sri Lanka and was adopted by her Swedish parents when she was three months old.

[8][2] Spending her childhood being raised in Sweden, she started riding horses at the age of 7 under the Swedish banner.

[2] She lives in Hamburg, Germany where she runs and manages her own equestrian business Grönwohldhof with her partner Manfred von Allwohrden.

[15] She also obtained the Swedish-Sri Lankan dual citizenship from the Embassy of Sri Lanka in Germany prior to the Olympics.