Mitochondrial ribosomal protein L35 (MRPL35) has been reported to contribute to the growth of non-small cell lung cancer (NSCLC) cells. However, the functions and mechanisms of MRPL35 on glutamine metabolism in NSCLC remain unclear. The detection of mRNA and protein of MRPL35, ubiquitin-specific protease 39 (USP39), and solute carrier family 7 member 5 (SLC7A5) was conducted using qRT-PCR and western blotting. Cell proliferation, apoptosis, and invasion were evaluated using the MTT assay, EdU assay, flow cytometry, and transwell assay, respectively. Glutamine metabolism was analyzed by detecting glutamine consumption, α-ketoglutarate level, and glutamate production. Cellular ubiquitination analyzed the deubiquitination effect of USP39 on MRPL35. An animal experiment was conducted for invivo analysis. MRPL35 was highly expressed in NSCLC tissues and cell lines, and high MRPL35 expression predicted poor outcome in NSCLC patients. Invitro analyses suggested that MRPL35 knockdown suppressed NSCLC cell proliferation, invasion, and glutamine metabolism. Moreover, MRPL35 silencing hindered tumor growth invivo. Mechanistically, USP39 stabilized MRPL35 expression by deubiquitination and then promoted NSCLC cell proliferation, invasion, and glutamine metabolism. In addition, MRPL35 positively affected SLC7A5 expression in NSCLC cells invitro and invivo. Moreover, the anticancer effects of MRPL35 silencing could be rescued by SLC7A5 overexpression in NSCLC cells. MRPL35 expression was stabilized by USP39-induced deubiquitination in NSCLC cells, and knockdown of MRPL35 suppressed NSCLC cell proliferation, invasion, and glutamine metabolism invitro and impeded tumor growth invivo by upregulating SLC7A5, providing a promising therapeutic target for NSCLC.