This study was designed to optimize different conditions for improving enzyme production by Penicillium brevicompactum AUMC 10987, and to precipitate and immobilize cellulases by cross-linking method using glutaraldehyde, magnetic nanocarriers and encapsulation using Ca-alginate. Maximum activity of cellulase was achieved in medium containing date palm leaves, sodium nitrate, after 9 days incubation at 30°C and pH 6. Solid state fermentation was more convenient method in cellulase production. After ammonium sulphate precipitation, enzyme activities exceeded two-folded, constructing more stability for the enzyme structure and giving maximum activities at 50℃ and pH 4.8. Hence, precipitated enzyme could work in higher temperature and acidity conditions. The immobilization of cellulases by encapsulation was the most valuable technique retaining the activity of enzyme. Moreover, the immobilized enzyme remained active up to 80°C, giving its maximum activity at 50°C and pH 5.5. Enzyme encapsulated within alginate beads is preferred due to easy for formulation, mild gelation conditions, non-toxic, biocompatibility, low cost and resistance to microbial attack. Magnetic nannocariers immobilized enzyme had opportunity to be reused after 4 cycles/16 hours. The current study could provide a robust and highly valuable immobilized enzyme for different industrial and biotechnological applications.