Muric led Cercle Brugge to eighth place in the Belgian top flight in his first year in charge.
Last season, he improved on that, leading them to a fifth-place finish in the regular season and a fourth-place finish in the season-ending playoffs.
This enabled them to advance to this season’s UEFA Europa League qualifying round, where they defeated Kilmarnock in two games, but were eliminated by Norwegian side Molde, dropping them to the Conference League.
He was sacked at the beginning of last month following a loss to bottom-placed Beerschot at Cercle, who are in the relegation play-offs.
Muslik becomes Argyle’s fourth permanent manager in the last 13 months.
Stephen Schumacher, who led the Pilgrims to the League One title in 2023, left the club in December of the same year to become Stoke City manager.
He was replaced by former England youth coach Ian Foster, but his three-month tenure saw the Pilgrims slip into the relegation zone, and it was the director of football who guided them to safety on the final day of the season. Neil Deusnip and Nanseki Bell.
Rooney, a former England national team captain, was appointed in the summer, but in his first half-season he had only won four league games, and on New Year’s Eve finished at the bottom of the club championship and with the worst defensive record in the English Football League.
