Background: The introduction of antiretroviral therapy (ART) significantly decreases the incidence of tuberculosis (TB) in Human Immunodeficiency Virus ( HIV) positive individuals during their follow-up. However, a considerable proportion is still co-infected with TB after ART initiation. Thus, this study aimed to assess the determinants of TB incidence among HIV-positive individuals during their ART follow-up in Addis Ababa, Ethiopia. Methods: A nested case-control study was conducted among HIV-positive individuals who were enrolled in ART clinics in Addis Ababa, Ethiopia from 2013 up to 2018. Cases were tuberculosis co-infected HIV positive individuals who were taking antiretroviral treatment, while controls were TB free HIV positive individuals who were taking antiretroviral treatment. The cases and controls are matched exactly in age and sex. Data were entered in EpiInfo version 7.1 and analyzed using SPSS version 20. Bivariable and multivariable conditional logistic regression were employed along with 95% CI. A P-value <0.05 in the multivariable analysis was considered statistically significant. Results: Fifty-seven cases were compared with 114 controls pair-matched exactly in age and sex. Accordingly, previous TB history (X ^2; 13.790 ^, P<0.001), baseline functional status (X ^2; 9.120 ^, P=0.010), baseline WHO clinical stage (X ^2; 10.083 ^, P=0.001), baseline hemoglobin value (X ^2; 6.985 ^, P=0.008), baseline body mass index (X ^2; 3.873 ^, P=0.049), isoniazid preventive treatment intake status (X ^2; 8.047 ^, P=0.005), baseline CD4 value (X ^2; 12.741 ^, P<0.001) and length of stay on ART (X ^2; 53.359 ^, P<0.001) were associated with TB infection. Length of stay on ART was found to be the statistically significant determinant of TB infection after ART initiation (aOR=5.925, 95%CI=2.649-13.250). Conclusion: Advanced clinical stages at the baseline, previous TB history, and not taking IPT were associated with TB infection. The long term ART exposure significantly decreases tuberculosis incidence in HIV patients. Screening HIV-positive patients for tuberculosis throughout their ART follow-up would be important early detection and treatment of tuberculosis.