This study investigated the effect of fermentation durations on the acha flour and resultant cookies. The acha sample was fermented at 24, 48 and 72 h, while the native acha flour served as the control sample. The functional, pasting, nutritional and micro-structural properties of the fermented acha flour and sensory evaluation of the cookies were examined. The results indicate significant differences (p<0.05) in the functional and pasting properties of the flour and cookies samples. An increase in fermentation duration enhances oil absorption capacity and dispersibility of the samples. The protein and ash content of the acha flour samples increased. The mineral element showed significant difference (p<0.05) in the calcium, sodium, and zinc content. The Fourier transform infrared (FTIR) spectra increase the band intensities. The peaks occurred in the range 3860 - 3650 cm ^-1. The X-ray diffraction (XRD) pattern revealed a slight increase in the crystallinity of the fermented flour samples. The flour samples exhibited an A-type XRD pattern while the cookies samples had V-type XRD pattern. Scanning electron microscopy (SEM) revealed that fermentation modified the microstructure of the flour, causing it to change from an irregular compact granular to a regular loose structure. Cookies samples produced from native and fermented acha flour were acceptable by the panelist. Therefore, cookies with improved nutritional and acceptable sensory properties were produced from native and acha flour fermented between 24 and 72 h. This suggests that fermented acha flour holds promise for various food applications, including complementary foods, and gel formulations with reduced syneresis.