Teacher Professional Development is a key component of educational reforms across the world with a view to improve teacher effectiveness and learner outcomes. Focus is shifting to collaborative teacher activities to improve learner outcomes. However, the effect of teacher participation in collaborative activities needs to be investigated due to persistent low learner outcomes in Kenya. The study adopted convergent parallel mixed methods approach design. A sample of 194 teachers in 68 public and private primary schools was selected using stratified random and purposive sampling. Twenty head teachers were purposively sampled. Data collection instruments were questionnaires, focus group discussion guide and semi structured interview guide. Data were analyzed using descriptiveand inferential statistics. The study established that teachers engaged in collaborative activities like sharing knowledge, peer coaching, lesson observation and team teaching. However, activities were top down lacking collegial approach. Teacher assistance in integrating technology was minimal due to inadequate ICT infrastructure, lack of skills among teachers and constraints in the time schedule. The study recommendedstakeholders supportfor variety ofcontinuous collaborativeprofessional development activities,improvement of ICT infrastructure and teacher capacitybuilding for improvedlearning outcomes in this digital era.