Bullying and violence has recently become a serious issue in schools among students in Tanzania and all over the world where children are faced with a high level of intimidation, violence and sexual harassment daily with weighty consequences on their social, healthy and emotional well-being. This study was about the physical and psychological bullying in secondary schools in Mwanza region, Tanzania. Specifically, it aimed at determining students' awareness of bullying existing in schools, identifying types of bullying existing in schools, establishing the causes of this phenomenon, investigating how bullying affects secondary school students' academics and lastly establishing students' views on punishment by teachers as bullying or otherwise. Both quantitative and qualitative approaches were applied as well as descriptive survey design. The data were collected by using questionnaires, interviews and documentary reviews. The targeted population of the study was 597 form four students in the selected schools in Mwanza region- Tanzania. Other study participants were school administrators including headmasters/headmistresses, discipline masters, school counsellors and ordinary teachers from 13 schools. Among the ordinary teachers were the university teacher trainees on practical training field schools. Among the research participants, bullies and victims, and policemen were included. The quantitative data were analyzed statistically by the use of SPSS software. Interviews data were also analyzed qualitatively by content analysis in terms of related reported speech and explanations. The results show that students are aware of bullying existing in schools. There is bullying in schools consisting of both physical and psychological ones, done by both students and teachers to students. The major causes of bullying observed included the gender variables, disciplinary procedures, classroom management practices, and poor students‟ behaviour and the reaction of teachers to students' poor academic achievement. The results further show that bullying affects both academic students' performance in their continue academic assessment test as well as the National examinations. It was also observed that bullying affects students' behaviour. The results also reveal that students perceive that some punishment especially corporal punishment is one of the type of bullying to them. Training to both students and teachers about bullying and violence existing is recommended. The provision of school facilities in adequate quantities to satisfy students' needs to reduce students inequalities is also recommended. The elimination of corporal punishment and discouraging bullying and harassment should be done by the use of preventive materials prepared. Bullying events and violence should be documented and evaluated twice a year. The feedback should be used for decision making for the preventive measures. The relations among students as well as between teachers should be monitored and evaluated regularly. Seminars for fighting children violence and bullying should be introduced in the country by using the creativities of trained and motivated facilitators. Only punishments which do not violate the children's human rights and which do not affect students learning activities should be administered. The heads of schools should be in the front line to stop bullying and violence behaviours. Clear directions should be given to all students regarding what they should do if they are bullied by fellow students or by teachers. For example, students' should report the bullying instant to the head of school.