On Friday, Croatian Paralympic athlete Bruno Bosnjak won the bronze in the men's snowboarding banked slalom.
Sokolovic had his legs amputated after a car accident when he was 15.
The silver medal in the sit-ski slalom went to Tyler Walker of the United States, while France's Frederic Francois won the bronze.
Sokolovic's gold and Bosnjak's bronze have put Croatia among 25 nations that have won medals at the PyeongChang Winter Paralympic Games.