We reveal that the GNL3 paralogue GTPase, GNL3L, associates with pre-ribosomes. We map RNA contact sites on GNL3L as well as GNL3L binding sites on pre-rRNAs. Lack of GNL3L impairs synthesis of the 60S rRNAs and expression of GTPase inactive GNL3L causes defects in early steps of pre-rRNA processing. Impaired GTP hydrolysis by GNL3L leads to its accumulation on pre-60S particles, together with other assembly factors with proximal binding sites.