<p>The creep response of organic rich shales to mechanical loading is often linked to viscous behaviour of organic matters and clay minerals at macro (core) scale without a full understanding of microscale mechanisms driving such macro-scale time-dependent observations. This in turn leads to models developed solely based on viscous behaviour of the materials and no other potential involved physical processes. To understand the microscale mechanisms driving macroscale time-dependent behaviour of organic-rich shales, we conduct a series of multiscale creep-damage experiments. These experiments include macroscale tests on shale samples from Beetaloo Basin, Northen Territory, Australia and microscale tests on shale and synthetic samples (hydrostone, hydrostonecement mixture, and Plaster of Paris (PoP) with rubber material embedded in their skeleton structure) using an optical micro-shear cell device. The result of macroscale experiments interestingly indicates that creep does not occur without damage to skeleton of the specimen. The digital image correlation analysis from microscale experiments further reveal the complex evolution of coupled damage and creep in the specimens. The findings from the microscale test also demonstrate that the characteristics of creep mechanisms are specific to the mechanical properties of materials, again highlighting the necessity of damage for creep occurrence. The understanding from microscale tests is further used to develop a multiscale creep constitutive model based on coupled continuum mechanics and non-equilibrium thermodynamics specifically focussing on energy dissipation encountered during damage driven creep process. The developed model is upscaled to the macroscale using energy conservation, revealing a consistent trend between the scales tested. This observation underscores the scalability and reliability of the developed model, shedding light on the fundamental mechanisms governing creep behaviour in brittle materials having soft constitutes across different scales.</p>