Background: Adequate descent housing is a universal human rights integral component. Resources’ costs and intensified rural-urban migration increase demand for sustainable housing. Modern knowledge-based-economy uses innovation. Construction industry uses product and process innovation to provide adequate and descent low-cost housing. Kenya adopted innovation practices of slum upgrading that uses cost effective locally available building materials. This study looked at the outcomes; social and economic impacts of innovative construction in housing in the Mathare Valley Slum upgrading project Methods: This post occupancy study used exploratorydescriptive research design. Random sampling was used to sample 384 users of low-cost housing projects in Mathare Valley, Nairobi County. Research instruments included semi-structured questionnaires and interview guides. Pilot study, validity and reliability tests ensured quality of study. Ethical considerations included university approval and consent. Statistical package for social sciences (SPSS) software version 21 was applied to compute the descriptive and inferential statistics. Findings: Slum-upgrading had significant-positive outcome on improved houses and community. Social impacts included communal facilities; assurance of security of tenure; and retained frameworks of establishments. Economic impacts included employment; affordable and durable units (p values <0.05). Upgrading process did not influence rent fees, was corrupt and led to displacement of residents. Conclusion: Slum upgrading process affected positively. Similar projects should consider residents in decision-making.