We have demonstrated that high internal phase emulsions (HIPE) can be obtained by mixing dispersed cellulose nanocrystals (CNCs) and oil. This is, however, possible only when a dilute Pickering emulsion is first prepared. The two-step process is made possible by the irreversible nature of CNC adsorption at the oil/water interface. Additional oil promotes swelling of the drops without phase inversion. Drop size is then driven by the CNC coverage ratio at the droplet surface, induced by a limited coalescence process. This process leads to a new interfacial networking organization. This study reveals a dual property of rod-shaped CNCs at the interface: i) possibility of dynamic displacement and ii) cooperative self-association leading to a percolating aggregate network. We have thereby demonstrated the possibility of obtaining oil as a gel stabilized by a pure cellulosic material.