This empirical study examines the impact of auditor attributes and firm size on financial reporting timeliness among listed firms in Nigeria. The study employs an ex-post facto type of research, with a quantitative design covering a ten-year period (2013–2022). The sample size comprises sixty-six (66) non-financial firms listed on the Nigerian Exchange Group (NGX). Based on data extracted from the audited annual reports of the sampled sixty-six firms, the robust regression model results reveal that joint audits contributed considerably to shorter financial reporting lags, underscoring the value of collaborative audit efforts in streamlining the audit process. Audit fees maintained a positive significant effect on the reporting lag of listed Nigerian firms. However, audit switch, client firm size, audit opinion, and audit firm size all maintained insignificant effects on the financial reporting timeliness of the Nigerian listed firms investigated. Therefore, the study recommends that listed firms should rather opt for affordable joint audits due to their efficiency in streamlining the audit process. Equally, the study recommends that listed firms should maintain long-term relationships with auditors to leverage increased familiarity, yet remain cautious of likely complacency and breach of auditing ethical guidelines that can arise from prolonged engagements.