Background: Implementation science (IS) has the potential to serve an important role in encouraging the successful uptake of evidence-based interventions. The current state of IS awareness and engagement among health researchers, however, is relatively unknown. Methods: To determine IS awareness and engagement among health researchers, we performed an online survey of health researchers in the USA in 2018. Basic science researchers were excluded from the sample. Engagement in and awareness of IS were measured with multiple questionnaire items that both directly and indirectly ask about IS methods used. Unrecognized IS engagement was defined as participating in research using IS elements and not indicating IS as a research method used. We performed simple logistic regressions and tested multivariable logistic regression models of researcher characteristics as predictors of IS engagement. Results: Of the 1767 health researchers who completed the survey, 68% stated they would be able to describe IS. Only 12.7% of the population self-identified as using IS methods. Of the researchers not self-identifying as using IS methods, 86.4% reported using the IS elements "at least some of the time." Nearly half (47.9%) reported using process/implementation evaluation, 89.2% use IS measures, 27.3% use IS frameworks, and 75.6% investigate or examine ways to integrate interventions into routine health settings. IS awareness significantly reduced the likelihood of all measures of unrecognized IS engagement (aOR 0.13, 95% CI 0.07 to 0.27, p < 0.001). Conclusion: Overall, awareness of IS is high among health researchers, yet there is also a high prevalence of unrecognized IS engagement. Efforts are needed to further disseminate what constitutes IS research and increase IS awareness among health researchers.