Objective: To assess the knowledge and practice of breastfeeding and the effects of lactation counseling, as a health promotion intervention, on breastfeeding duration and exclusive breastfeeding (EBF) among Saudi women. Methods: In this quasi-experimental design study, 664 mothers attending a women's hospital from January 2017 to December 2018 were interviewed. Women were allocated into two groups, control and intervention groups, based on received lactation counseling. Interviews were performed using a structured questionnaire collecting data on the sociodemographic characteristics, knowledge, attitude and practice of breastfeeding mothers. A chi-squared test was used to determine the level of significance on breastfeeding practices among two groups. Propensity score matching was presented to control confounders, as women cannot be randomly assigned to lactation counseling. Results: Of 664 women, 592 were Saudi nationals, and the majority of mothers were literate (96.2%). A significantly higher number of mothers in the consultation group were employed as compared with the non-consultation group (p = 0.015). One third (33.3%) of the women practiced EBF, while 39.8% preferred mixed feeding for the first six months of the infant's life. The consultation group demonstrated a significantly higher response rate in their knowledge on the benefits of breastfeeding in babies (increased intelligence; p < 0.05) and mothers (breast engorgement; p = 0.004), colostrum and its importance (p = 0.027) and effective breastfeeding practices (initiate breastfeeding within 30 min after birth (p = 0.01), baby needs 10-20 min between each feed (p = 0.009), breastfeeding should last for 6 months (p = 0.01)) compared with the non-consultation group. The age of weaning (5.3 ± 2.8 vs. 5.9 ± 3.2 months) was similar across both the groups. However, "the intended duration of BF" was higher in the non-consultation group, and the difference was statistically significant (p = 0.002). The mean weight and length of the baby at follow-up were similar in both groups, with no statistical significance. The duration of exclusive breastfeeding among two groups was not statistically significantly different (8.7 ± 6.9 vs. 8.1 ± 7.1 weeks). Mothers in the two groups were satisfied with their breastfeeding experience. The mean scores lie within the range of 4.2 to 5.0. Baby age (month), mother LoE, mother job and type of BF were controlled for, and the propensity-score-matched 62.5% sample from both the groups yielded the same results. Conclusions: Breastfeeding women in our study showed a fair knowledge of EBF. However, the duration of actual EBF was very short, and the counseling intervention showed no impact on EBF in our study population. We recommend interventions that are tailored to the needs of this population, while identifying factors that improve breastfeeding practice among mothers.