Oligonucleotide arrays are one of the most used technologies in genotyping and gene expression experiments. Here, a previously developed chitosan-based platform is characterized in its binding of unmodified oligonucleotides, increasing the cost effectiveness of the microarray production process. The unmodified oligonucleotides on the activated chitosan surface showed the same or better performances than amino-modified probes. Moreover, we show applications in genotyping (a ligation detection reaction experiment on cyanobacteria) and in gene expression (on peach RNA samples). The platform was demonstrated to be reliable, robust, and reproducible for immobilizing unmodified oligonucleotides in high quality oligonucleotide array fabrication.