BACKGROUND: Despite large investments in HIV testing, only an estimated 45% of HIV-infected people in sub-Saharan Africa know their HIV status. Optimum methods for maximising population-level testing remain unknown. We sought to show the effectiveness of a hybrid mobile HIV testing approach at achieving population-wide testing coverage. METHODS: We enumerated adult (≥15 years) residents of 32 communities in Uganda (n=20) and Kenya (n=12) using a door-to-door census. Stable residence was defined as living in the community for at least 6 months in the past year. In each community, we did 2 week multiple-disease community health campaigns (CHCs) that included HIV testing, counselling, and referral to care if HIV infected; people who did not participate in the CHCs were approached for home-based testing (HBT) for 1-2 months within the 1-6 months after the CHC. We measured population HIV testing coverage and predictors of testing via HBT rather than CHC and non-testing. FINDINGS: From April 2, 2013, to June 8, 2014, 168,772 adult residents were enumerated in the door-to-door census. HIV testing was achieved in 131,307 (89%) of 146,906 adults with stable residence. 13,043 of 136,033 (9·6%, 95% CI 9·4-9·8) adults with and without stable residence had HIV; median CD4 count was 514 cells per μL (IQR 355-703). Among 131,307 adults with stable residence tested, 56,106 (43%) reported no previous testing. Among 13,043 HIV-infected adults, 4932 (38%) were unaware of their status. Among 105,170 CHC attendees with stable residence 104,635 (99%) accepted HIV testing. Of 131,307 adults with stable residence tested, 104,635 (80%; range 60-93% across communities) tested via CHCs. In multivariable analyses of adults with stable residence, predictors of non-testing included being male (risk ratio [RR] 1·52, 95% CI 1·48-1·56), single marital status (1·70, 1·66-1·75), age 30-39 years (1·58, 1·52-1·65 vs 15-19 years), residence in Kenya (1·46, 1·41-1·50), and migration out of the community for at least 1 month in the past year (1·60, 1·53-1·68). Compared with unemployed people, testing for HIV was more common among farmers (RR 0·73, 95% CI 0·67-0·79) and students (0·73, 0·69-0·77); and compared with people with no education, testing was more common in those with primary education (0·84, 0·80-0·89). INTERPRETATION: A hybrid, mobile approach of multiple-disease CHCs followed by HBT allowed for flexibility at the community and individual level to help reach testing coverage goals. Men and mobile populations remain challenges for universal testing. FUNDING: National Institutes of Health and President's Emergency Plan for AIDS Relief.