Acute malnutrition (AM) causes large loss of life and disability in children in Africa. Researchers are testing innovative approaches to increase efficiency of treatment programs. This paper presents results of a cost-effectiveness analysis of one such program in the Democratic Republic of the Congo (DRC) based on a secondary analysis of a randomized controlled trial Optimizing Treatment for Acute Malnutrition (OptiMA), conducted in DRC in 2018-20. 896 children aged 6-59 months with a mid-upper arm circumference (MUAC) <125 mm or with oedema were treated and followed for six months. Cost-effectiveness of OptiMA using ready-to-use therapeutic food (RUTF) at a tapered dose was compared with the standard national program in which severe cases (SAM) received RUTF proportional to weight, and moderate cases (MAM) were referred to another clinic for a fixed dose regimen of ready-to-use supplementary food. Cost analysis from provider perspective used data collected during the trial and from administrative records. Statistical differences were derived using t-tests. The mean cost per enrolled child under OptiMA was $123 [95%CI: 114-132], not statistically different from the standard group ($127 [95%CI: 118-136], p=0.549), while treatment success (i.e. recovery to MUAC > 125mm and no relapse for 6 months) under OptiMA was 9 percentage points higher (72% vs 63%, p=0.004). Among children with SAM at enrollment, there was no significant difference in treatment success between OptiMA and standard (70% vs 62%, p=0.12) but OptiMA's mean cost per enrolled child was 23% lower ($128 vs $166, p<0.0001). OptiMA was more effective at preventing progression to SAM among those enrolled with MAM (5% vs 16%, p<0.0001) with an incremental cost-effectiveness ratio (ICER) of $234 per progression to SAM prevented. Overall, OptiMA had significantly better outcomes and was no more expensive than standard care. Its adoption could enable more children to be successfully treated in contexts where therapeutic food products are scarce.