MicroRNA-155 (miR-155) is an important pro-inflammatory molecule that controls immune responses in both physiological and pathological settings. Although miR-155 is well studied, little is known about its transcriptional regulation in T cells. We sought to further understand the mechanisms by which miR-155 transcription is induced following T cell activation. We found that miR-155 transcription is dependent on the activity of the Notch and NFkB signaling pathways. It was determined that the canonical Notch signaling pathway was involved in this regulation and that it was dependent upon the activation of NFkB. Additional work confirmed that both NFkB and Notch1 directly bind to the promoter of miR-155. These results support a model by which the canonical Notch signaling pathway cooperates with NFkB to directly promote the transcription of miR-155 following T cell activation. In conclusion, we have identified a novel mechanism of miR-155 regulation that will contribute to a greater understanding of its role in the immune system.