Introduction: Food security and dietary diversity are critical in ensuring the nutritional and dietary adequacy of mothers. However, since the COVID-19 outbreak, it has become more challenging for mothers to maintain a healthy and varied diet, as more households are reported to be food insecure. Thus, this study aimed to assess food insecurity and its determinants, as well as to determine how it relates to dietary diversity. Methods: A cross-sectional study comprising 200 of B40 mothers with children under the age of two who resided in metropolitan regions of Selangor was conducted. Household Food Insecurity Access Scale (HFIAS) and Minimum Dietary Diversity for Women (MDDW) questionnaires were used to measure food insecurity and dietary diversity, respectively. Results: About 67% of mothers experienced food insecurity and 29.5% experienced dietary monotony. Less than 12 years of education (AOR=4.89, 95% CI=1.87-12.83) and living in a family with six or more people (AOR=3.48, 95% CI=1.20-11.20) were significantly associated with food insecurity. Besides, mothers with a monotonous diet were eight times more likely to be food insecure (AOR=8.03, 95% CI=2.67-24.05). Higher odds of dietary monotony were associated with less than 12 years of education (AOR=2.46, 95% CI=1.13-5.35) and household income contributor of not more than one person (AOR=3.78, 95% CI=1.66-8.60). Conclusion: Food insecurity was associated with an increased chance of dietary monotony among low-socioeconomic women residing in urban community. Therefore, identifying and addressing issues related to poor dietary diversity may allow for preventive and proactive measures to improve their nutritional status and well-being.