This report examines the characteristics and treatment outcomes of patients with tuberculosis (TB) who are coinfected with HIV in Japan. Active TB cases newly notified to the Japan Tuberculosis Surveillance system during 2012–2020 were analysed retrospectively, during which 379 HIV-positive TB cases were reported. The proportion of HIV-positive cases among those with known HIV status increased, from 1.9% (62/3328) in 2012 to 3.5% (31/877) in 2020. The proportion of those with unknown HIV testing status was consistently high, at approximately 60%, and the proportion of those who did not undergo HIV testing increased significantly, from 21.6% (4601/21 283) in 2012 to 33.7% (4292/12 739) in 2020. The proportion of foreign-born cases more than tripled, from 14.5% (9/62) in 2012 to 45.2% (14/31) in 2020. The TB treatment success rate was higher among HIV-negative than HIV-positive cases (72.7% [3796/5222] versus 60.3% [88/146]), and among Japan-born than foreign-born HIV-positive patients (65.6% [61/93] versus 50.9% [27/53]), owing largely to the high rate of foreign-born cases transferring to care outside Japan. The increasing proportion of HIV positivity among TB cases tested for HIV in this study requires ongoing monitoring, especially among foreign-born persons. However, because the number of reported cases was small, and there was low completeness of reporting of HIV testing data in the TB surveillance system, these results should be interpreted with caution. Encouraging more complete data collection by training public health nurses who complete TB case interviews and ensuring ongoing monitoring of patients with TB/HIV coinfection are recommended.