Knowledge and attitude towards mental illness play major role in the recognition, management, sociocultural factors and health seeking behavior among those with mental disorders. The study aim was to determine the knowledge and attitude among Nyamagana community members towards mental illness, Tanzania; A descriptive cross-sectional quantitative study involving 384 participants from sample population aged 18 years and above who were mentally health and semi-structured questionnaires was used to collect data. The results 110 (28.8%) respondents have good knowledge toward mental illness, about 292(76%) have negative attitude towards mentally ill people, 92(24%) respondents have positive attitude toward people who are mentally ill. More over about 318 (82.9%) respondents agreed that care and support of family and friends, could help people with mental illness to get rehabilitation while 66(17.1%) respondents disagreed on the care and support of the family and friends could help mentally ill people to get rehabilitation; The findings show most have poor knowledge and negative attitudes towards people with mental illness and may impair their social reintegration in the community. There’s need to develop strategies to enlighten the public regarding nature of mental illness so as to foster acceptance of people with mental illness by the community members.