This paper examines whether the duration of equity overvaluation influences managers’ choice to use different earnings management mechanisms, and how corporate governance and the Australian Securities and Investment Commission’s underlying earnings disclosure guidelines influence managers’ choices. The study uses a sample of Australian Securities Exchange 200 firms between 2009 and 2016. The findings show that on average, firms are more likely to engage in accruals earnings management in the early stage of overvaluation. In the later stages, firms are more likely to disclose underlying earnings aggressively to sustain overvaluation. The study also finds that firms with a high proportion of independent directors on the board prefer to disclose underlying earnings aggressively to sustain the equity overvaluation; firms with a low proportion of independent directors on the board prefer to use both accruals earnings management and aggressive underlying earnings disclosure to sustain the overvaluation. Another finding is that firms that conform to the Commission’s underlying earnings disclosure guidelines use neither accruals earnings management nor aggressive underlying earnings disclosure to sustain overvaluation, but firms that do not conform to the guidelines use both of these mechanisms to sustain overvaluation.