The emergence of engineered living materials (ELMs) has introduced a novel approach to creating functional composites by combining living and nonliving elements- commonly hydrogels - to produce advanced materials with both structural and biological properties. Hydrogels, which often mimic the extracellular matrix (ECM) of organisms, create a supportive environment for microorganisms by providing essential nutrients and promoting cell adhesion within their structure, and are therefore favored for producing ELMs. ELMs are generally created by seeding microorganisms onto hydrogel-based scaffolds or mixing them with hydrogels to form bioinks that can be printed or molded. Various hydrogels, such as gelatin, alginate, collagen, and gelatin/alginate blends, are commonly used to produce microorganism-laden bioinks, enabling three-dimensional (3D) printing of ELMs through techniques like inkjetting, laser printing, extrusion, and stereolithography. Furthermore, biomineralization commonly occurs in organic matrices that are similar to hydrogel systems. Of different hydrogels, gelatin, a natural protein derived from collagen and closely mimicking the ECM, is particularly favored to be a hydrogel material for ELMs. Gelatin contains an RGD sequence that promotes cellular attachment and growth and includes charged amino acids like aspartic and glutamic acids, which can bind calcium ions. This binding facilitates ionotropic processes, adjusting the local chemical environment to support nucleation and crystal growth during biomineralization. Additionally, the ability of gelatin to crosslink at bacteria-compatible temperatures makes it ideal for biomineralization applications. However, the printability of gelatin poses a significant challenge for its wide adoption, typically requiring strict temperature control, chemical modifications, and/or additives to make it suitable for printing. The objective of this study is to develop a microorganism-laden gelatin microgel and gelatin solution composite bioink for the self-supported printing of ELMs, which can be further mineralized via calcium carbonate precipitation by the microorganisms laden in the bioink. This approach overcomes the aforementioned gelatin printing-related limitations by creating a yield-stress bioink capable of being printed and physically cross-linked in air, which is prepared by combining chemically cross-linked gelatin microgels with a gelatin solution, transglutaminase (TG), and microorganism to form a microorganism-laden, gelatin-based composite bioink. Specifically, this composite bioink incorporates Sporosarcina pasteurii (S. pasteurii), facilitating microbial-induced calcium carbonate precipitation (MICP) to produce rigid, versatile calcium carbonate structures in this study. The gelatin microgels function as a rheology modifier, making the resulting composite bioink a yield-stress fluid, which remains solid-like until a stress higher than the yield stress is applied. When the stress exceeds the yield point, the composite liquefies and becomes liquid-like, enabling smooth deposition during printing; once printed, it returns to be solid-like, retaining the shape being deposited as the result of the physical cross-linking process due to the microgel jamming and unjamming transitions. As such, these transitions from a solid-like state to a liquid-like state and back to a solid-like state enables self-supported printing in air. Then the resulting structures are completely cross-linked enzymatically by TG in the composite bioink. The printability of the proposed gelatin composite bioink has been demonstrated by fabricating solid cylinders and tubes using extrusion printing. The printed samples have been cultured, dried, and further analyzed with scanning electron microscopy (SEM) and X-ray diffraction (XRD) to confirm calcium carbonate deposition, along with mechanical testing. The biomineralized structures have achieved a calcium carbonate content exceeding 50 wt% and the compressive strength up to 2.5 MPa. SEM and XRD analyses have verified successful mineral deposition throughout the structures, including both the outer surface and internal cross sections. The biomineralized materials hold promise for various engineering applications. This study contributes to the field of ELMs by providing a cost-effective, energy-efficient method for creating 3D-printed biocomposites with high mechanical strength and biocompatibility, paving the way for further innovations in biomineralized materials for medical and ecological applications such as bone tissue engineering and coral restoration.