Topological braiding of complex bands in non-Hermitian systems has emerged as a powerful framework for exploring novel topological phases. Although extensively investigated in static and Floquet-Bloch settings, such braiding is conventionally characterized by finite braid groups ${\mathrm{B}}_q$, in which only subsets of bands participate in braiding processes. Here, we unveil a new class of spectral topology in non-Hermitian space-time crystals, called the global Floquet-band braiding, where all Floquet bands intertwine globally in generalized momentum-energy space. This phenomenon arises from the space-time translational symmetry, which enables single-orbital band crossings. The resulting braiding involves an infinite number of Floquet bands, referred to as infinite-band braiding. Under the rational space-time modulation, the multiband periodicity endows the system with a cylindrical topology, allowing the global braiding structure to be effectively described by cylindrical braid groups $\mathrm{C}{\mathrm{B}}_q$. Crucially, this topology transcends the conventional framework of finite braid groups, marking a fundamental expansion of non-Hermitian spectral topology. In experiments, we implement a reconfigurable topolectrical circuit that realizes a part of the space-time band braiding. By exploiting space-time translation symmetry, we reconstruct the global Floquet-band braiding characterized by $\mathrm{C}{\mathrm{B}}_5$. Our work establishes the non-Hermitian space-time crystal as a novel platform for engineering unprecedented non-Hermitian topological matter beyond existing paradigms.

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• Topolectrical circuits
• Topological phases of matter
• Floquet systems
• Non-Hermitian systems
• Bloch-Floquet theorem