The aims of the present study were to assess secular trends in breast-feeding and to explore associations between age at introduction of solid foods and breast-feeding duration. Data from three national dietary surveys in Norway were used, including infants born in 1998 (Spedkost 1, n 1537), 2006 (Spedkost 2, n 1490) and 2018 (Spedkost 3, n 1831). In all surveys, around 80 % of the infants were breastfed at 6 months of age. At 12 months of age, breast-feeding rate was 41 % in Spedkost 1, increasing to 48 % in Spedkost 2 and 51 % in Spedkost 3. Compared with earlier introduction, introduction of solid foods at ≥ 5 months of age was associated with a lower risk of breast-feeding cessation during the first year of life in the two most recent Spedkost surveys. In Spedkost 2, the adjusted hazard ratio for breast-feeding cessation during the first year of life for those introduced to solid foods at ≥ 5 months of age was 0·43 (95 % CI (0·31, 0·60)), P < 0·001, while the corresponding number in Spedkost 3 was 0·44 (95 % CI (0·29, 0·67)), P < 0·001. In conclusion, breast-feeding at infant age 12 months increased over time. Introduction of solid foods at ≥ 5 months of age was positively associated with breast-feeding duration in the two most recent Spedkost surveys. As breast-feeding contributes to numerous health benefits for infant and mother, and possibly improved dietary sustainability in infancy, findings point to the importance of continued protection, support and promotion of breast-feeding.