Yes - but with limitations.

BBQ on beachSummer Visitors
While there is no law preventing bbq's on the beach, there are laws which are in place for the safety and comfort of other visitors.
During the summer months the increased volume of people using the beach makes it difficult to have a bbq safely. The beach is patrolled very efficiently by the MNR (Ministry of Natural Resources) officers so it is not a good idea to light up your propane or charcoal bbq on the beach. However, many people do bring bbq's and they tend to use them in the grassy area right beside the beach.
For those of you who have never been to Wasaga Beach, the grassy areas are quite literally next to the sand, so you will not be inconvenienced. Bring your bbq and enjoy a nice picnic where it is safe to do so but use common sense to make sure your smoke, embers, fire or hot bbq will not put any other visitors in harm's way. Find a spot for your bbq where people cannot bump it or trip over it and you should not be asked to move it.

Off-Season Visitors
Common sense should always prevail when you are about to light a bbq. During the off-season, there are less people on the beach and you might be able to find an area right on the beach where a bbq would be fine.

High winds are common in the fall. Do be aware that it is unlawful to cook on the beach if there are high winds, if it is raining or if you are too close to combustibles. Your embers and smoke should not endanger or bother anyone else. Have fun!
BBQ - Grills in Picnic Areas for Public Use

Some visitors might remember that there were bbq grills in some picnic areas which were intended for public use. These have been removed due to "abuse". I don't dare want to think about what sort of abuse these grills endured but suffice to say you were always better off bringing your own.