Writing in his latest newsletter to staff, Ian Craig said investment would continue and fears that trams would squeeze busses out were unfounded.
And he moved to reassure drivers and other staff members that there would be no job cuts as a result of the trams project.
Following approval of tram line one from Newhaven to Edinburgh Airport, Mr Craig said: "So what does this mean for Lothian Buses and what will it mean to you [the staff] personally?
"Firstly, I can confirm that the shareholders and directors remain fully committed to growing and developing Lothian Buses.
"Investment in fleet, premises and people will continue in order to meet the needs of our customers now and in the future.
"After all, even when trams start running, the vast majority of the population of the city will be served by buses, so the bus network has to grow and develop to serve the 92 per cent of the city's population who live in areas not served by the tram line."
He added that the 19 buses which would be sacrificed to make way for the trams only accounted for three and a half per cent of the fleet and would not make much of an impact.
He said: "There will certainly not be any staff redundancies."