The hallmark of amyloid diseases is deposition of misfolded proteins as amyloid fibrils in the interstitium of target organs. Amyloid deposits surround cells, distorting the micro and macro-architecture of the extracellular space and profoundly changing the physical and molecular properties of this compartment. In the heart, extracellular matrix (ECM) remodeling has a profound impact on the mechanical properties of this target organ and on the physiology and metabolism of resident cells. This review critically summarizes the available knowledge on ECM alterations in cardiac amyloidosis, with the goal of providing an overview on how biochemical, biophysical and anatomical modifications are interrelated, and how ECM remodeling participates in the pathophysiology of this unique type of cardiopathy.