BackgroundHigh completed fertility among married and cohabiting women has profound consequences, including straining resources, increasing healthcare challenges, and contributing to educational and gender inequalities. This study examined the factors associated with high completed fertility among married and cohabiting women aged 40–49 years in Ghana.MethodsData for the study was sourced from the 2022 Ghana Demographic and Health Survey (GDHS). A spatial map was used to present the women's geographic variations in high completed fertility. A mixed-effect multilevel binary logistic regression analysis was performed to identify the factors associated with high completed fertility. The findings were presented as adjusted odds ratios (aOR) with a 95% confidence interval (CI).ResultsThe national proportion of high completed fertility among married and cohabiting women aged 40–49 years in Ghana was 52.0% [48.8, 55.2]. Women who were Ga/Dangme/Ewe by tribe [aOR = 2.32, 95% CI = 1.06, 5.08] had higher odds of high completed fertility than Akans. Women who indicated 6 + as their ideal number of children had a higher [aOR = 5.60, 95% CI = 2.90, 10.82] likelihood of high completed fertility compared to those whose ideal number of children was 0–3. Those who were using contraceptives at the time of the survey had a higher [aOR = 2.31, 95% CI = 1.17, 4.55] likelihood of high completed fertility compared to those who were not using contraceptives. Women with secondary/higher education [aOR = 0.32, 95% CI = 0.17, 0.58] had lower odds of high completed fertility than those without no formal education. Women with females as household heads [aOR = 0.56, 95% CI = 0.33, 0.95] had lower odds of high completed fertility than males. Women in Volta, Western North, Ahafo, and Bono regions had lower odds of high completed fertility compared to those living in the Northeast region, with the lowest odds among those living in the Volta region [aOR = 0.08, 95% CI = 0.02, 0.40].ConclusionHigh completed fertility is prevalent in Ghana, with more than half of married and cohabiting women having at least five or more children. The government and policymakers in Ghana should promote education for women, increase culturally sensitive family planning programs, increase access to family planning resources, address ideal family size preferences, and improve understanding of contraceptive use.