A modular support base for supporting an item of furniture comprising: - at least two longitudinal members arranged facing each other at a predefined distance depending on a width of the item of furniture or a part of the furniture to be supported; each longitudinal member of said plurality of longitudinal members extending along a longitudinal direction between a front portion and a rear portion; - at least one front cross member extending along a transverse direction with respect to said longitudinal direction between two of its own front ends; said front cross member being interposed between two front portions of two longitudinal members facing each other so that each front end of said front cross member can be connected with a respective front portion of said longitudinal members; - at least one rear cross member extending along a transverse direction with respect to said longitudinal direction between two of its own rear ends; said rear cross member being interposed between two rear portions of two longitudinal members facing each other so that each rear end of said rear cross member can be connected with a respective rear portion of said longitudinal members; - a junction means for joining said cross members (3, 4) to said longitudinal members, wherein said junction means is interposed between each front end of said front cross member and said respective front portions of the longitudinal members; said junction means being interposed between each rear end of said rear cross member and said respective rear portions of the longitudinal members; said junction means being configurable between a coupled condition, wherein the ends (3a, 4a) of the cross members (3, 4) are connected to the longitudinal members forming said modular support base, and an uncoupled condition, wherein the cross members (3, 4) are deconstrained from the longitudinal members therefore the modular base is formed by a plurality of mutually deconstrained components; each longitudinal member has a resting surface for supporting at least one base of the item of furniture and a surface facing the floor opposite said resting surface, wherein each longitudinal member has at least one housing at said surface facing the floor preconfigured for the coupling of at least one base for a foot or a foot; characterised in that at least one longitudinal member comprises, along at least one of its lateral surfaces facing outwards and arranged according to a vertical plane, at least one coupling means for coupling with at least one appendage of the item of furniture, wherein said coupling means are pin elements. - at least two longitudinal members arranged facing each other at a predefined distance depending on a width of the item of furniture or a part of the furniture to be supported; each longitudinal member of said plurality of longitudinal members extending along a longitudinal direction between a front portion and a rear portion; - at least one front cross member extending along a transverse direction with respect to said longitudinal direction between two of its own front ends; said front cross member being interposed between two front portions of two longitudinal members facing each other so that each front end of said front cross member can be connected with a respective front portion of said longitudinal members; - at least one rear cross member extending along a transverse direction with respect to said longitudinal direction between two of its own rear ends; said rear cross member being interposed between two rear portions of two longitudinal members facing each other so that each rear end of said rear cross member can be connected with a respective rear portion of said longitudinal members; - a junction means for joining said cross members (3, 4) to said longitudinal members, wherein said junction means is interposed between each front end of said front cross member and said respective front portions of the longitudinal members; said junction means being interposed between each rear end of said rear cross member and said respective rear portions of the longitudinal members; said junction means being configurable between a coupled condition, wherein the ends (3a, 4a) of the cross members (3, 4) are connected to the longitudinal members forming said modular support base, and an uncoupled condition, wherein the cross members (3, 4) are deconstrained from the longitudinal members therefore the modular base is formed by a plurality of mutually deconstrained components; each longitudinal member has a resting surface for supporting at least one base of the item of furniture and a surface facing the floor opposite said resting surface, wherein each longitudinal member has at least one housing at said surface facing the floor preconfigured for the coupling of at least one base for a foot or a foot;