PINK1-Parkin mediated mitophagy, a selective form of autophagy, represents an important mechanism in mitochondrial quality control (MQC) via clearance of damaged mitochondria. Although it is well known that the conjugation of mammalian ATG8s to phosphatidylethanolamine (PE) is a key step in autophagy, its role in mitophagy remains controversial. In this study, we attempted to clarify the role of the mATG8-conjugation system in mitophagy by generating knockouts of the mATG8-conjugation machinery. Unexpectedly, we show that mitochondria could still be cleared in the absence of mATG8 lipidation, in a process that was found to be independent of lysosomal degradation. Instead, mitochondria were found to be cleared via a secretory autophagy pathway, resulting in the extracellular release of mitochondria, in a process we defined as autophagic secretion of mitochondria (ASM). Functionally, increased ASM promoted the activation of the innate immune cGAS-STING pathway in recipient cells. Overall, data from this study reveal ASM as a novel mechanism in MQC, especially when the cellular mATG8-conjugation machinery is dysfunctional.