3-hydroxypropionate dehydrogenase (NADP<sup>+</sup>) () is an enzyme with systematic name 3-hydroxypropionate:NADP<sup>+</sup> oxidoreductase. This enzyme catalyses the following chemical reaction:
This enzyme catalyses the reduction of malonate semialdehyde to 3-hydroxypropionate, which is a key step in the 3-hydroxypropionate and the 3-hydroxypropionate/4-hydroxybutyrate cycles, autotrophic CO<sub>2</sub> fixation pathways found in some green non-sulfur phototrophic bacteria and archaea, respectively. The enzyme from Chloroflexus aurantiacus is bifunctional, and also catalyses the upstream reaction in the pathway, EC 1.2.1.75. Different from EC 1.1.1.59, 3-hydroxypropionate dehydrogenase (NAD<sup>+</sup>), by cofactor preference.