Novel imidazole derivatives of the low molecular weight chitosan N-(2-hydroxypropyl)-1H-1,2,3-triazol-4-yl)methyl)-1-methyl-1H-imidazol-3-ium chitosan chloride (NMIC) were synthesized using copper-catalyzed azide–alkyne cycloaddition (CuAAC). The degrees of substitution (DSs) for the new derivatives were 18–76%. All chitosan derivatives (2000 µg/mL) were completely soluble in water. The antimicrobial activity of the new compounds against E. coli and S. epidermidis was studied. The effect of chitosan derivatives on blood and its components was studied. NMIC samples (DS 34–76%) at a concentration <10 μg/mL had no effect on blood and plasma coagulation. Chitosan derivatives (DS 18–76%) at concentrations of ≥83 μg/mL in blood and ≥116.3 μg/mL in plasma resulted in a prolongation of the clotting time of blood and plasma, positively related to the DS. At concentrations up to 9.1 μg/mL, NMIC did not independently provoke platelet aggregation. The degree of erythrocyte hemolysis upon contact with NMIC samples (2.5–2500 μg/mL) was below 4%. The inhibition of blood/plasma coagulation indicates the promising use of the studied samples to modify the surface of medical materials in order to achieve thromboresistance.