Background Discrimination of people living with HIV/AIDS is one of the reported obstacles to the achievement of universal access to HIV/AIDS prevention, treatment, care, and support programs. Many international agencies have made combating HIV/AIDS stigma and discrimination a top priority. However, previous evidence in different parts of Africa revealed that the magnitude of HIV/AIDS-related discriminatory attitude is significantly high. Objective To assess discriminatory attitude towards people living with HIV/AIDS and its associated factors among the adult population in 15 sub-Saharan African nations. Methods We have used the 15 Demographic and Health Survey data that were conducted in sub-Saharan Africa (SSA) from 2015 to 2019/20. Each country’s data was appended and a total weighted sample of 318,186 (unweighted sample = 315,448) adults who had ever heard of AIDS was used for the final analysis. The two discriminatory attitude questions were used to get the outcome variable and those who answered “Yes” or “don’t know” for both questions were counted as if they had no discriminatory attitude towards people living with HIV/AIDS. To assess the factors associated with discriminatory attitude towards people living with HIV/AIDS, we have fitted a multilevel binary logistic regression model. Bivariable analysis was done to select eligible variables for the multivariable analysis. Finally, variables with p<0.05, in the multivariable analysis, were considered as significant predictors of discriminatory attitude towards people living with HIV/AIDS. Results The prevalence of discriminatory attitude towards HIV/AIDS in the 15 sub-Saharan African nations was 47.08% (95% CI: 47.08, 47.42), which ranges from 17.64% (95% CI: 17.22, 18.07) in Malawi to 79.75% (95% CI: 79.02, 80.45) in Guinea. In the multivariable analysis, both individual level and community level variables were significantly associated with discriminatory attitude towards people living with HIV/AIDS. Being younger age, no formal education, never married, low socioeconomic status, male-headed household, non-contraceptive use, no mass media exposure, and incorrect comprehensive knowledge towards HIV/AIDS were among the individual-level factors that were associated with higher odds of discriminatory attitude towards people living with HIV/AIDS. While being from urban residence and the western SSA region were among the community-level factors that were significantly associated with higher odds discriminatory attitude towards people living with HIV/AIDS. Conclusion The prevalence of discriminatory attitude towards people living with HIV/AIDS in 15 sub-Saharan African nations was high. Both individual and community-level factors were associated with discriminatory attitude towards people living with HIV/AIDS. Therefore, special attention should be given to those who are poor, uneducated, and younger adults. In addition, it is better to strengthen the accessibilities of different media for adult populations to create an appropriate attitude towards people with HIV/AIDS.