An inkjet printhead assembly includes an elongate support. A plurality of printhead modules is arranged end-to-end along the support. Each printhead module includes a carrier carrying an elongate printhead configured to eject ink. Ends of each carrier define one or more complementary formations so that each adjacent pair of carriers is nested together. The printheads are positioned on the carriers to form a pair of parallel rows of spaced apart printheads with one of the rows being longitudinally offset with respect to the other row so that each printhead in the one row overlaps each adjacent printhead in the other row to enable printing without gaps along the support.