Abstract Mucosal‐associated invariant T (MAIT) cells are characterized by rapid responses to nonpeptide antigens via invariant T‐cell receptors (TCR), and expression of an “effector‐like” T‐cell phenotype. The transcription factor promyelocytic leukemia zinc finger (PLZF) is crucial for defining the function of MAIT cells and other unconventional T cells; however, the transcriptional programs that direct MAIT cell development are not fully elucidated. Here, we show that the canonical NF‐κB transcription factor RelA is critical for MAIT cell thymic development, but not responsiveness to antigen, whereas NF‐κB1 and c‐Rel make more limited contributions. MAIT cell development is also impaired in the absence of the linear ubiquitin signaling complex (LUBAC), an upstream regulator of NF‐κB signaling, implicating this pathway in establishing the MAIT cell pool. Collectively, these data suggest LUBAC and NF‐κB signals as elements of the transcriptional network controlling MAIT cell development.