Eldritch Invocations aren't spells but features. so while the teleport is magical, it isn't spellcasting. You can thus cast any spells with your action when using it.
Additionally, Eldritch Blast is a cantrip. Even if teleporting as a bonus action were a leveled spell, you would be able to cast a cantrip with your main action.
If I use the bonus action to teleport behind a hexed enemy can I cast Eldritch blast as my action?
Eldritch Invocations aren't spells but features. so while the teleport is magical, it isn't spellcasting. You can thus cast any spells with your action when using it.
Additionally, Eldritch Blast is a cantrip. Even if teleporting as a bonus action were a leveled spell, you would be able to cast a cantrip with your main action.
What they said ⬆️.
It isn't a spell and wouldn't matter for cantrips anyway (but it is important to know).