Nanoscale composition fluctuations in Li2O–SiO2‐based glasses were analyzed and discussed from the data on the structure and crystallization process reported so far to enter deeply into the medium‐range ordered structure of multicomponent oxide glasses. Li2O is proposed to have a strong tendency for dynamical heterogeneous structure, that is, the formation of fragile Li2O‐rich regions with small SiO2 contents, resulting in the initial crystallization of metastable Li2SiO3 prior to the formation of stable Li2Si2O5 in Li2O–2SiO2‐based glasses. Li2O–Ga2O3/Nb2O5–SiO2 glasses are proposed to have nanoscale composition fluctuations of Li2O–Ga2O3/Nb2O5‐rich regions, resulting in the initial formation of LiGa5O8 and LiNbO3 nanocrystals. In Li2O–Al2O3–SiO2 glasses, the distribution width of composition fluctuations is proposed to be narrow, resulting in the initial crystallization of metastable β‐quartz solid solutions Li2O·Al2O3·nSiO2 (n = 6–8). Additive P2O5 and NiO leading to an enhanced nucleation are proposed to be present in fragile Li2O‐rich regions.