The huge amounts of smoke produced by the disas­trous 2019-2020 Australian bushfires are shown to be a previously unrecognized forcing that affected the onset of a La Niña event in 2020 and resulted in processes that sustained that “triple-dip La Niña” over the next sev­eral years with significant impacts worldwide.  Initialized Earth system model hindcasts with E3S­Mv2 and CESM2 with and without the effects of the smoke show Bjerknes feedback, first trig­gered by the Australian bushfire smoke through interactions with clouds in the eastern Pacific, sustained the triple-dip La Niña conditions. Important processes include an inten­sified anomalous Walker Circulation that connected strengthened precipitation and ascent in the west­ern Pacific with anomalous subsidence, an invigo­rated South Pacific High, stronger Trades, and cool­er SSTs across the tropical Pacific. In the model hindcasts and observations, the North Pacific Meridional Mode is important for ending the multi-year event. Understanding this newly discovered role of wildfire smoke points to mechanisms involved with the onset, dura­tion, and transition out of the multi-year La Niña to El Niño with implications for current predictions of an El Niño this year.