Background: The first two years of a child’s life is a critical window during which the foundations for healthy growth and development are built. An estimated 32% of children less than 5 years of age in developing countries are stunted and 10% are wasted. Inappropriate complementary feeding practices are a major contributor to poor nutrition status among children under two in Ethiopia. Therefore, timely starting nutritionally-adequate, safe, age-appropriate complementary feeding at sixth months of age is recommended for better health and development of infants and to do this mathernal knowledge, attitude and practice on complementary child feeding are critical isssues. Objective: Assessement of the knowledge, attitude & practices of mothers on complementary child feeding and identifying associated factors in Farta Woreda, Northwest Ethiopia from December to June, 2017. Methods: A community based cross-sectional study was conducted in Farta Woreda. A total of 520 mothers were intervied using interviewer administered, pre-tested structured questionnaires and face to face interview technique. Multistage sampling method was used. The degree of association between independent and dependent variables was assessed using odds ratio with 95% confidence interval and P-Value <0.05. Result: Out of five hundred twenty seven participants to be interviewed, 520 participants with 98.7% response rate were participated.The proportion of poor knowledge, attitude and practice of respondants on complementary child feeding were 33.5% , 62.1% and 47.3% respectively.The study showed that 488(93.7%) of the participans know when to start complementary food to their child and 450(86.5%) of the them practically started complementary food to their child at 6 months age. Adjusting all other factors in the final model, the multivariate analysis showed that: Marital status AOR [95% CI] =3.29[1.097, 9.883], Type of Family AOR [95% CI] = 1.78[1.130, 2.801], Health Education AOR [95% CI] = 17.83[5.993, 53.060] had significant association with knowledge, Occupation of mothers AOR [95% CI] = 0.30[0.100, 0.924] and household income AOR [95% CI] =2.08[1.86, 3.127] had significant association with poor Attitude and Marital status AOR [95% CI] =2.51[1.288, 4.896], No of <5 children AOR [95% CI] = 2.22[1.073, 4.582] and household income AOR [95% CI] =1.85[1.246, 2.751] had significant association with poor practice of mothers on complementary child feeding. Hence skill based awareness creation on complementary child feeding at community level should be given due attention by the respected concerned bodies. Key words: Complementary feeding, timely starting, knowledge, attitude and practice, Farta Woreda.