Purpose: To describe the choroidal thickness (ChT) in a large sample of young adults with the aim of establishing a normative ChT profile reference in this demographic cohort and explore its association with best-corrected visual acuity (BCVA). Design: Cross-sectional study. Methods: From a single center, 741 young adults (19-30 years of age, 49% male) were recruited to undergo a comprehensive ophthalmic examination, including BCVA measurement, post-cycloplegic autorefraction, ocular biometry, tonometry, and spectral-domain optical coherence tomography (SD-OCT) imaging. The enhanced depth imaging mode on the SD-OCT was used. The main outcome measure was the central macular ChT (0.5-mm radius around the fovea). The ChTs at the inner (between 0.5-mm and 1.5-mm radius) and outer macular rings (between 1.5-mm and 2.5-mm radius) were also measured. Results: The median central macular ChT was 370 μm (interquartile range 312-406 μm). The choroid was thickest at the superior-inner, inferior-inner, and central macular regions (370-373 μm) and thinnest nasally at the outer macular region (median 256 μm). Decreased central macular ChT was associated with younger age, female sex, nonwhite ethnicities, and myopia (P ≤ .013). There was a significant association between better BCVA and increased central macular ChT (P < .001), after adjusting for age, sex, ethnicity, and ocular measures. His relationship was only apparent in eyes with central macular ChTs <300 μm (P = .019) and absent in eyes with ChTs >300 μm. Conclusions: The central ChT of young adults was 370 μm. There was a significant association between worse BCVA and thinner choroids below a threshold of 300 μm, raising the possibility that ChT could be predictive of visual function.