In this study, we developed new types of amidoxime functionalized nanofibrous mats and utilized them for trace level detection or extraction of uranium ions. Electrospun poly(acrylonitrile) (PAN-ESF) mats had been enriched with surface rich cyano groups using a polymer (Silica-CN) to obtain Silica-CN incorporated electrospun composite nanofibers (PAN/Silica-CN-ESCF) and subsequently, the mats were post modified to obtain amidoxime enriched composite nanofibrous (AOER-ESCF) mats. For comparative purposes, pristine PAN electrospun fibers (PAN-ESF) were also modified to obtain simple amidoximated electrospun fibers (AO-ESF). The changes in the surface morphology and structural characteristics between PAN-ESF, PAN/Silica-CN-ESCF, AO-ESF and AOER-ESCF were evaluated by field emission scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The uranium ion sorption capacity of the AO-ESF and AOER-ESCF adsorbents was evaluated and compared. The nanostructures and the additional component in the ESCF provide a high surface area and cyano groups for enriching the amidoxime groups to obtain AOER-ESCF. Our results show that AOER-ESCF adsorbent has a high uranium ion extraction capacity for a wider uranium concentration range compared to simple AO-ESF. This new strategy of modifying ESF has also been extended to the development of lithium ion extraction adsorbents through the inclusion of spinel into the PAN-ESF.