BACKGROUND: Globally, the increasing use of digital technologies such as mobile phones and the internet has allowed for the development of innovative mobile health interventions, particularly for reaching and engaging with youth. However, there is a risk that using such technologies may exclude those who lack access to them. OBJECTIVE: In this study, we investigated the sociodemographic factors associated with mobile phone ownership, internet use, and social media use among youth in Zimbabwe. METHODS: A population-based prevalence survey was conducted in 24 urban and periurban communities across 3 provinces of Zimbabwe (Harare, Mashonaland East, and Bulawayo). Youths aged 18 to 24 years resident in randomly selected households in the study communities completed an interviewer-administered questionnaire. The primary outcomes were mobile phone ownership and current internet and social media use. A household wealth indicator was developed using principal components analysis, based on household asset ownership. Multivariable logistic regression was used to investigate the factors associated with each primary outcome. Age, sex, and province were considered a priori confounders. Household wealth, marital status, education level, employment status, time lived at current address, and HIV status were included in the final multivariable model if there was an age-, sex-, and province-adjusted association with a primary outcome on univariable analysis at a significance level of P<.10. RESULTS: Of the 17,636 participants assessed for the primary outcome, 16,370 (92.82%) had access to a mobile phone, and 15,454 (87.63%) owned a mobile phone. Among participants with access to a mobile phone, 58.61% (9594/16,370) and 57.79% (9460/16,370), respectively, used internet and social media at least weekly. Older age (adjusted odds ratio [aOR] 1.76, 95% CI 1.55-2.00), increasing wealth (ranging from aOR 1.85, 95% CI 1.58-2.16, for wealth quintile 2 to aOR 3.80, 95% CI 3.00-4.80, for wealth quintile 5, with quintile 1 as reference), and higher education level (secondary: aOR 1.96, 95% CI 1.60-2.39; tertiary: aOR 8.36, 95% CI 5.29-13.20) were associated with mobile phone ownership. Older age, male sex, increasing wealth, having never been married, higher education level, being in education or formal employment, and having lived at the same address for ≥2 years were associated with higher levels of internet and social media use. CONCLUSIONS: While mobile phone ownership was near-universal, over one-third of youths in urban and periurban settings did not have access to the internet and social media. Access to the internet and social media use were strongly associated with household wealth and education level. Mobile health interventions must ensure that they do not amplify existing inequalities in access to health care. Such interventions must be accompanied by alternative strategies to engage and enroll individuals without internet or social media access to prevent the exclusion of young people by sex and socioeconomic status.