This study assessed the influence of school heads' direct supervision on teacher role performance in public senior high schools. The study adopted the embedded mixed methods design. Slovin's formula, the proportional allocation method, and simple random and purposive sampling were used to select a sample of 617 respondents comprising 295 teachers, 222 class prefects, 86 Heads of Department, 13 school heads and 1 Regional Director for the Inspectorate Division of the Ghana Education Service. Data were collected through questionnaires and interview guides. Quantitative data were analyzed using frequencies, means and multiple regression whereas patterns and themes were developed for the analysis of qualitative data. The study found that school heads allocated very little time for supervision of lesson planning and delivery of teachers. The study established that school heads' lesson planning supervision (p= 0.043< 0.05) and lesson delivery supervision (p= 0.035< 0.05) had a significant influence on teacher role performance. Therefore, the study recommends the Ghana Education Service to dedicate a greater portion of the promotion requirement of the school heads to evidence of direct supervision of teachers and a reduction in the teaching load of Heads of Department by the school head to enable them play more instrumental roles in the instructional supervision process.