Geneva Airport to Chamonix by bus

A regular efficient bus service links Chamonix directly with Geneva Airport and also stops in Geneva itself.
Chamonix to Geneva Airport bus timetable from Altibus
(English available, look in the bottom left for the link as, inexplicably, it's not possible to link directly to it)
The last buses go at around 5 pm and you need to allow plenty of time to get there. If the times are not suitable, an airport transfer service can take you to Chamonix, often for a comparable price