<P><B>Abstract</B></P> <P>Increasing the microbial CO<SUB>2</SUB>-fixing efficiency often requires supplying sufficient ATP and redirecting carbon flux for the production of metabolites. However, addressing these two issues concurrently remains a challenge. Here, we present a combinational strategy based on a synergetic CO<SUB>2</SUB>-fixing pathway that combines an ATP-generating carboxylation reaction in the central metabolic pathway with the ATP-consuming RuBisCO shunt in the carbon fixation pathway. This strategy provides enough ATP to improve the efficiency of CO<SUB>2</SUB> fixation and simultaneously rewires the CO<SUB>2</SUB>-fixing pathway to the central metabolic pathway for the biosynthesis of chemicals. We demonstrate the application of this strategy by increasing the CO<SUB>2</SUB>-fixing rate and malate production in the autotroph <I>Synechococcus elongatus</I> by 110% and to 260 μM respectively<I>,</I> as well as increasing these two factors in the heterotrophic CO<SUB>2</SUB>-fixing <I>Escherichia coli</I> by 870% and to 387 mM respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed a combinational strategy to increase the microbial CO<SUB>2</SUB>-fixing efficiency. </LI> <LI> We combined ATP-generating carboxylation with the ATP-consuming RuBisCO shunt. </LI> <LI> This strategy was applied to increase CO<SUB>2</SUB>-fixing rate in <I>Synechococcus elongatus</I> by 110%. </LI> <LI> It also improved malate production of <I>S. elongatus</I> to 260 μM. </LI> <LI> These factors also improved in <I>Escherichia coli</I> (870% and 387 mM, respectively). </LI> </UL> </P>