Formate, a biologically accessible form of CO2, has attracted interest as a renewable feedstock for bioproduction. However, approaches are needed to investigate efficient routes for biological formate assimilation due to its toxicity and limited utilization by microorganisms. Cell-free systems hold promise due to their potential for efficient use of carbon and energy sources and compatibility with diverse feedstocks. However, bioproduction using purified cell-free systems is limited by costly enzyme purification, whereas lysate-based systems must overcome loss of flux to background reactions in the cell extract. Here, we engineer anE. coli-based system for an eight-enzyme pathway from DNA and incorporate strategies to regenerate cofactors and minimize loss of flux through background reactions. We produce the industrial di-acid malate from glycine, bicarbonate, and formate by engineering the carbon-conserving reductive TCA and formate assimilation pathways. We show thatin situregeneration of NADH drives metabolic flux towards malate, improving titer by 15-fold. Background reactions can also be reduced 6-fold by diluting the lysate following expression and introducing chemical inhibitors of competing reactions. Together, these results establish a carbon-conserving, lysate-based cell-free platform for malate production, producing 64 μM malate after 8 hours. This system conserves 43% of carbon otherwise lost as CO2and incorporates 0.13 mol CO2equivalents/mol glycine fed. Finally, techno-economic analysis of cell-free malate production from formate revealed that the high cost of lysate is a key challenge to the economic feasibility of the process, even assuming efficient cofactor recycling. This work demonstrates the capabilities of cell-free expression systems for both the prototyping of carbon-conserving pathways and the sustainable bioproduction of platform chemicals.HighlightsSuccessfully engineered the carbon-conserving reductive TCA and formate assimilation pathways in a lysate-based cell-free system for production of the C4 industrial di-acid malate from C1 and C2 feedstocks.Achieved a 6-fold reduction in competition from the endogenous cell-free metabolism by blocking TCA activity using small-molecule inhibitors and lysate dilution.Increased accumulation of malate by 15-fold in a single-step reaction using cell-free expression of an enzymatic cofactor regeneration system.Techno-economic analysis identified routes for economically feasible production of malate from renewable feedstocks in a cell-free system by improving conversion efficiency and reducing lysate cost.Graphical Abstract