How do say 'As you all know' - Todo el mundo sabe...?!?!
Todo el mundo is an expression which means everyone e.g. Me pregunto eso a todo el mundo = I ask everyone that. Me llamo kenneth pero todo el mundo me llama ken.which roughly means my name is Kenneth but everyone calls me Ken.
Como sabéis = as you all know.
Consider that sometimes it's better for translation purposes to think of figures of speech that have the same meaning than it is to make a word for word (literal) translation. That is, to look for a figurative translation.
Think about, in this case, the English expression "As everyone/everybody knows". It's easier to find a Spanish translation for this "means alike" expression. In your request, think about:
"As everyone knows" = "Como todos saben"
As all the world knows - Como todo el mundo sabe
Como ustedes ya saben