An inkjet printhead assembly includes an elongate chassis defining a plurality of ink supply channels. A sealing shim defines sets of apertures and is configured to be mounted in sealing engagement with the chassis so that the sets are aligned with respective channels. A plurality of printhead carriers is configured to be received on the shim. Each printhead carrier defines galleries configured to engage in fluid communication with respective sets and further defines a printhead recess terminating the galleries. Ink ejection printhead segments each define ink supply holes, and are configured to be received within respective printhead recesses so that ink can be supplied to the printhead segments through the holes via the galleries.