Commercial chitosan – without any post-modification with active Bronsted or Lewis acid centers – was found to be a highly efficient renewable and recoverable bio-polymer catalyst for the rapid and convenient synthesis of α-amino nitriles or imines from aromatic aldehydes and amines under mild reaction conditions at room temperature in high to quantitative yields. The α-amino nitrile derivatives were prepared through the Strecker reaction using trimethylsilyl cyanide (TMSCN) and catalyzed by chitosan as a heterogeneous bifunctional organocatalyst.