How do I blend these three edges into a smooth rounded corner? Baring in mind I’m using SketchUp Web version.
You want to get your head around the Follow Me tool.

With SketchUp native tools the answer is to create a sphere or half sphere and cut away the faces you don’t need. Follow Me cannot create a clean corner when the radius of the path equals the radius of the profile.
Or with @Box’s method and the ground radius slightly bigger than the vertical radius.
Only a difference of say 1% between radii will make a nice corner:
So still just a few clicks.
@Box
Thank you for responding, however, instead, I am getting this. Does it not work on web version maybe or am I doing something wrong?
You only need a portion of what you have drawn to follow around… make the section you are using with follow me 1/2 the length of the width.
Also - how many segments in your arc? If this is very small you will have issues… you may need to reduce the number of segments or scale things up.
What is your end goal for the model?



