Over the past two decades, multiple empirical studies have examined how teacher audio feedback works in EFL/ESL writing courses. This review explores instructor audio feedback studies in higher education writing contexts. Seventy empirical studies were identified in literature searches published between 2000 and 2022 in several academic databases. Then, based on exclusion and inclusion criteria, thirteen relevant studies were reviewed. The results indicate that interest in instructor audio feedback research has risen since 2000. This overview presents what empirical studies on teacher audio feedback in L2 writing courses aimed to find out, how they were conducted, and what they found. As many research designs and findings were underexplored, more studies are required to investigate this feedback type to benefit L2 writing learning and teaching and enrich studies on audio feedback practices. The gaps identified in the selected studies offer ideas for future explorations of teacher audio feedback in L2 writing contexts.