Building a sustainable society that respects planetary boundaries and ensures future livelihoods is a critical challenge. A circular bioeconomy using microorganisms to produce industrially relevant products could be an alternative to the linear produce-use-waste economy, dependent on fossil resources. However, this bioeconomy must rely on raw materials that do not increase the pressure on ecosystems or compete with food production. One-carbon (C1) molecules, such as methanol and formate, are promising feedstocks as they can be derived from CO2 and green hydrogen, thus avoiding the need for additional arable land. This work explores the potential of the methylotrophic yeast Ogataea polymorpha as a chassis organism for converting methanol and formate into industrial products. Since O. polymorpha is a non-conventional yeast, there is only a limited number of genetic tools available. This work expands the genetic toolbox for O. polymorpha by a set of well-characterized promoters and terminators for methanol-based cultivations. These genetic elements were then applied to produce various low molecular weight biochemicals from methanol. Strain engineering and adaptive laboratory evolution led to an O. polymorpha strain that produced lactate at g/L scale and exhibited an increased growth rate on methanol. Methanol toxicity was identified to be a major obstacle to the cultivation of O. polymorpha at laboratory scale. Therefore, methanol feeding strategies were further refined for strains developed to produce malate. Malate export across the plasma membrane was identified as a key factor influencing malate production from methanol. The yeast was also engineered to produce acetone and isoprene, demonstrating its potential to produce a variety of chemicals using methanol as a carbon source. The study further explored formate as a novel C1 substrate for O. polymorpha, by characterizing its native C1 metabolism and introducing formate-assimilating enzymes into the yeast's peroxisomes. Although growth with formate as the sole carbon source could not be demonstrated, it was shown that low concentrations of formate as a co-substrate can have a positive effect on biomass formation, likely due to the electrons that the oxidation of formate to CO2 can provide for cellular metabolism. These findings therefore provide a valuable knowledge base for the future development of methylotrophic yeast strains that could contribute to a circular bioeconomy based on C1 molecules.