This cross-sectional study aimed to assess the knowledge and practice of body mechanics (BMs) among pregnant women with lumbopelvic pain (LPP) and to determine the association between LPP and BMs. The study was conducted using a purposive sample of 110 pregnant women with LPP. A structured questionnaire was used to collect data. Descriptive statistics, a chi-square test (X2) (α = 5%), and a multinomial regression model were used. More than half (53.6%) of the participants were knowledgeable about BMs, and 55.5% did not perform their daily activities correctly. There was a significant association between the level of BMs knowledge and the severity of pain (p = 0.024), and the level of practice was significantly associated with pain severity (p = 0.038). The odds ratio (OR = 5.105) was higher among those with severe pain and those who did not practice correct BMs. The odds ratio (OR = 4.581) was higher among those with very severe pain and poor knowledge of BMs. Inadequate knowledge and limited practice of daily activities according to BMs principles were significantly associated with pain intensity in pregnant women with LPP in the 14th − 30th weeks of gestation.