Yes. There is no restriction on creature size.
Which is what makes repelling blast a very nice invocation.
If you go to Combat rules in chapter 9, the 'shove' action has a size limitation.
The target of your shove must be no more than one size larger than
you, and it must be within your reach.(Basic Rules, p. 77)
The rules text for repelling blast has no such limitation on the creature being hit with it.
When you hit a creature with eldritch blast, you can push the creature
up to 10 feet away from you in a straight line.
Why did I bring up Chapter 9? Because not all DMs have played all classes nor memorized all class abilities. As an example, my brother (DM) had never seen a warlock in play that had repelling blast as an invocation. The first time I pushed a huge creature back (a hill giant) his response was "Isn't that too big for you to push back?" to which I replied "this invocation does not have the limitation that a shove does." He trusts me so off the road it went.
We played on and after the game I showed him the difference. His response was to nod his head.