Sexually transmitted infections (STIs) pose a considerable concern for global healthcare systems. We examined the prevalence and correlates of self-reported STIs (SR-STIs) among men and women in Papua New Guinea. A total of 7,195 women and 4,069 men from Papua New Guinea who participated in the 2016-2018 Demographic and Health Survey were included in this study. Percentages were used to summarize the prevalence of SR-STIs among men and women. A multivariable multilevel binary logistic regression was used to examine the correlates of SR-STIs in men and women. An overall 5.9% and 4.6% prevalence of SR-STIs were recorded among women and men, respectively, in Papua New Guinea. The odds of SR-STIs were higher among women who ever tested for HIV (aOR = 2.47, CI: 1.80-3.39), those who had first sex below 20 years (aOR = 1.76, CI: 1.10-2.80), those who watched television less than once a week (aOR = 1.83, CI: 1.13-2.95) and those from the Highlands and Momase regions (aOR = 5.55, CI: 3.30-9.33) compared to their counterparts who never tested for HIV, who had their first sexual intercourse when they were 20 years and above, who did not watch television at all, and those from the Southern Region. For men, the odds of SR-STIs were high among those who ever tested for HIV (aOR = 1.65, CI: 1.11-2.45), those with one (aOR= 2.08, CI: 1.05-4.14) and two or more (aOR = 3.77, CI: 1.49, 9.52) sexual partners excluding spouse in the 12 months preceding the survey, those living in the Highlands region (aOR = 2.52, CI: 1.48-4.29), and those living in communities with medium literacy level (aOR = 2.33, CI: 1.38-3.94) compared to their counterparts who had never tested for HIV, those with zero sexual partners excluding their spouse in the 12 months preceding the survey, those living in the Southern region, and those living in communities with low literacy levels. We recommend that the National AIDS Council of Papua New Guinea through the National HIV and STI 2018-2022 Strategy program should be realigned to address these correlates and ensure that more sexual and reproductive health resources are provided to men and women in the Highlands and Momase regions.