Back ground: Appropriate nutrient intake and/or complementary feeding in quantity, bioavailability and timely in infancy period are essential for optimal growth and development. Initiation of safe and nutritionally adequate complementary foods at 6 month is crucial to achieve optimal growth, development and health. Nutritional deficiencies during this period can lead stunting which cause to impaired cognitive development and low economic productivity which become difficult to reverse later in life. Objective: To assess of timely introduce of complementary feeding practices and associated factors among mothers with children aged 6-23months at lay armachiho woreda Northwest Ethiopia. Methods: community based cross sectional study was conducted among 564 children aged 6-23 months. The data were entered Epi-info version 7 and transferred, cleaned, coded and analyzed using SPSS version 20.Bivariate and multivariate logistic regression analyses were used to identify factors associated with complementary feeding practices. Adjusted odd ratio with corresponding 95% interval was calculated to show the strength of association. A p value of less than 0.05will be used to declare significance of association. Result: the prevalence of timely introduce of complementary feeding at six month was 64.4 (95% CI= 60.4, 67.9), Mothers occupation of housewife, antenatal follow up, institutional delivery and postnatal follow up were found to be independent predictor of increase timely introduce of complementary feeding practices. Conclusion: Mothers introduce complementary feeding at six month of child age 64.4% as recommended. This was relatively lower prevalence than WHO recommendation 80% and greater 80%. All mothers must be encouraged to make ANC follow up, delivered in health institution and postnatal care follow up.