My first impulse is to say No, the canvas is too wimpy. However.

It depends. What tess are you going to use, small and light-weight delicate, or heavy and bulky? Do you plan to grout it?

IF you decide to do this, I might suggest that you saturate the canvas with Mod Podge first, so that it is stiff and resistant to everything (including wet stuff like glue and grout mixed with water).

Another thought is that mesh tape reinforcing stuff. I haven't done any of this, so perhaps someone who has will come in here.

Pictures, please!

I made this lampshade to match a table I made. Painted the canvas shade and used GE II to glue the glitter tiles on and the trim around the edge. As long as you don't put a lot of stuff on it, it will be okay. This has held up through 2 moves and being stored. Definitely no grout and if you did mosaic the whole thing you wouldn't get much light. Even just painting the shade it doesn't give off a lot of light.

Mosaic it with paper or fabric. Dark means little light it's true. Use modpodge or white glue thinned with water and a bit of urethane. If you use fabric pieces it can help to treat them with modpodge before cutting to prevent fraying.
Good luck.
Kathy