Objective To examine associations between television (TV) viewing, reading, physical activity (PA), and psychosocial well‐being among a representative sample of young South Korean children aged 0–5 years. Methods Findings are based on 1,774 children who participated in the Korea Children and Youth Survey. All measures were questionnaire‐derived. Psychosocial well‐being included social, interactive, and emotional skills (α = .7–.9), and the top quartile denoted high psychosocial well‐being. Multiple logistic regressions were performed to examine relationships after controlling for several confounders. Results Compared to children who participated in PA for <1 hr/week, those who participated in PA for 1‐ <3 hr/week were more likely to show high emotional skills (odds ratio [OR]: 1.40, 95% confidence interval [CI] [1.02, 1.93]), and those who participated ≥3 hr/week were more likely to show high social (OR: 2.01, 95% CI [1.45, 2.78]) and interactive skills (OR: 1.39, 95% CI [1.01, 1.92]). During weekdays, children who read 1– <3 hr/day and ≥3 hr/day, compared to <1 hr/day, were more likely to show high social (OR: 1.61, 95% CI [1.20, 2.16] and OR: 2.47, 95% CI [1.31, 4.67]) and emotional skills (OR: 1.57, 95% CI [1.16, 2.13] and OR: 2.58, 95% CI [1.34, 4.98]). In addition, children who read 1– <3 hr/day, compared to <1 hr/day, were more likely to show high interactive skills (OR: 1.44, 95% CI [1.08, 1.92]). Similar findings for reading on weekends were observed. TV viewing was not associated with social skills or interactive skills. TV viewing for 1– <3 hr/day, compared to <1 hr/day, was associated with increased odds of high emotional skills (OR: 1.71, 95% CI [1.28, 2.27] on weekdays; OR: 1.90, 95% CI [1.39, 2.61] on weekends). Conclusion PA and reading primarily showed favourable associations with psychosocial well‐being, whereas TV viewing did not; thus, PA or reading may be a better option over TV viewing for optimal psychosocial well‐being among young South Korean children. These findings should be confirmed with stronger study designs.