To determine the effect of an oral health literacy intervention on oral health literacy-related outcomes among rural-dwelling Indigenous Australian adults. A total of 400 Indigenous adults (203 intervention and 197 control participants) were recruited into a randomized controlled trial; a functional, context-specific oral health literacy interventions were developed and implemented by Indigenous staff. The intervention comprised five sessions, each lasting 1.5 hours, across a 1-year period. The primary outcome was oral health literacy as assessed by the HeLD-14 instrument, with secondary outcomes including the social impact of oral disease, and psychosocial and knowledge-related factors. Three scenarios were used in data analysis: (I) intention to treat; (II) as treated and; (III) adherence only. Multiple imputation (MI) was used to replace missing data. The proportion reporting that "water with fluoride" was good increased in the intervention group within both crude and MI data analyses under the three scenarios. Other crude data analysis yielded no significant differences for either primary or secondary outcomes between intervention and control groups under the three scenarios. After MI, oral health literacy improved when assessed under scenario II (mean change=1.3, 95% CI: 1.1, 1.6). Improvements under three scenarios were also observed for the Oral Health Impact Profile (OHIP-14; mean change ranged from -0.7 to -3.8), sense of control (mean change ranged from 0.4 to 1.1), oral health-related fatalism (mean change ranged from -0.7 to -0.4) and perceived stress (mean change ranged from -2.1 to -1.1). The proportion reporting that "cordial was good" decreased in the intervention group from MI analysis under scenarios II and III. A context-specific oral health literacy intervention was partially successful in improving oral health literacy and oral health literacy-related outcomes in this vulnerable population, but only after MI. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.