Do I need to hire a Mountain Guide to climb Mont Blanc?

No, there is no requirement to hire a Guide and, happily, in the mountains we are all free to climb as we please. However if you do not already have the mountaineering skills described above, and want to maintain a reasonable margin of safety then yes, you would be strongly advised to hire a fully qualified IFMGA Mountain Guide. Not only will they offer you a training and acclimatisation programme and look after you on the mountain they will also arrange other aspects of the ascent like planning the schedule, booking the huts and often making difficult decisions about whether or not it is safe to continue in the prevailing weather.