Although numerous reports on the synthesis of atom‐specific 15N‐labeled nucleosides exist, fast and facile access to the corresponding phosphoramidites for RNA solid‐phase synthesis is still lacking. This situation represents a severe bottleneck for NMR spectroscopic investigations on functional RNAs. Here, we present optimized procedures to speed up the synthesis of 15N(1) adenosine and 15N(1) guanosine amidites, which are the much needed counterparts of the more straightforward‐to‐achieve 15N(3) uridine and 15N(3) cytidine amidites in order to tap full potential of 1H/15N/15N‐COSY experiments for directly monitoring individual Watson–Crick base pairs in RNA. Demonstrated for two preQ1 riboswitch systems, we exemplify a versatile concept for individual base‐pair labeling in the analysis of conformationally flexible RNAs when competing structures and conformational dynamics are encountered.