During the COVID-19 pandemic global breakout, Brunei responded to the first wave of the contagious disease with a national lock-down, resulting in traditional face-to-face education to move entirely to online teaching and learning mode. This paper reports on teachers’ feedback on the new school norm of online teaching and learning mode, their preparation and implementation of the online teaching and learning mode; their expectations on their teaching performance and learning activities; and challenges they experienced. Most research suggested that the competencies, skills, and experiences of K-12 teachers implementing online teaching and learning mode are distinct from teachers teaching the traditional face to face mode. There is a substantial number of studies on teachers’ blended teaching mode of online and face-to-face mode. There is a shortage of research on teaching competencies, skills, and fully online teaching and learning mode experiences. The purpose of the current study is to identify teachers’ competencies and skills in implementing fully online teaching and learning mode during the COVID-19 school lock-down. An online survey questionnaire was distributed to private school teachers in Brunei at the end of the second term of school (conducted fully online). Some preliminary findings revealed teachers’ positive perceptions about their competencies, their concern about online learning risks and privacy, and their intentions to implement blended teaching and learning mode post-COVID-19 lock-down. This study has shown that teachers quickly adapted themselves to online teaching and learning mode’s immediate needs due to the COVID-19 lock-down. This study suggests that teachers respond positively to online teaching and learning mode and require more professional development to improve their competencies and skills for online teaching and learning.