The former Hearts of Oak forward spent most of his career in the Superettan league before helping Halmstads to promotion last year.
Karim started in the season opener on Sunday against BK Hacken, lasting 74 minutes as the hosts secured all three points from a Mikael Boman 84th minute strike.
“Alhamdulillah to start the season with a win and finally making my Allsvenskan debut after years of hard work discipline and perseverance,” he posted on Twitter after the game.
Compatriots Phil Ofosu-Ayeh and Thomas Boakye were also in action for Halmstads on Sunday.
Sadat Karim played a vital role as HBK returned to the top-flight, playing 28 games and scoring six times to end the clubs three year stay in the second tier.
The 29-year-old previously played for Landskrona BoIS and Prespa Birlik in Sweden.
