Depression is one of the leading mental health concerns among science undergraduates, and rates of student depression increased during the COVID-19 pandemic. Revealing one's depression in an academic science environment can be helpful, because it can result in increased support from others. However, depression is considered a concealable stigmatized identity, meaning that it can be kept hidden and may carry a stigma. A national pivot to online learning owing to COVID-19 not only increased the need to bolster student mental health, but also presented a novel learning environment. However, it is unclear to what extent students revealed their depression in science courses and why. We surveyed 1179 undergraduates with depression at a research-intensive institution about whether they had revealed their depression to an online college science instructor. Very few undergraduates (5.9%) had revealed their depression to online science instructors; students who identify as LGBTQ+, have lower grade point averages, or experience more severe depression were more likely to reveal their depression to an instructor. Undergraduates reported potential benefits from doing so, including building a connection with the instructor and receiving accommodations. This work provides insight into steps science instructors can take to foster inclusive course environments for students with depression.