Chamonix to Geneva transportation

I did the My Way Alps tour last fall 2022. We stayed at the hotel next to the bus station. Chamonix is small so no matter where the tour stays it will be easy to get to the bus station. I bought a 12 euro ticket with Swiss Tours to Geneva but there were two or three other buses leaving with other companies at about . the same time or within minutes of each other. I bought the ticket about two months in advance. I did notice people buying tickets that morning at the bus station window so don’t know if you really need to buy in advance but that was last year. With more people traveling this year I would just buy the ticket now. The bus stopped in downtown Geneva and then went on to the airport. There were empty seats on the bus. Several tour members booked with Bla Bla bus and said that was fine. RS tours suggested using a different bus company, Mountain Dropoffs, or something like that but I had already bought my ticket for substantially less by that point. The transfer was seamless. Just ask at the bus station window about the departure times or look at the schedule posted on the window and be at the station before the bus leaves. There are signs for each bus company and sure enough, right on time the Swiss Tours bus pulled up to the sign, the bus driver put our luggage under the bus and we boarded and left. Hope this helps.

Has anyone done this in reverse?

You can also take the train from Chamonix to Geneva. For up to date info, you can check the schedule of the trains on the Swiss SBB website or app - https://www.sbb.ch/en. Have a great vacation!