It is a phrase, "looked (me) up and down". Hope this helps :)

Looked me up and down is correct.

I agree with Camilla. "looked me up and down" is the way we say this. I don't know why, it just is.

Some possible ways Ivy: At first, he didn't recognize me. Until he looked at me up and down. Or At first, he didn't recognize me. Prior to checking me out head to toe. Or At first glance he didn't recognize me. So then he, with much curiosity, looked me up and down (or looked at me up and down). There are many more creative ways to say this however, suffice it to say, at the end of the day, your sentence, "At first he didn't recognize me. He looked me up and down" is fine. Even "... He looked at me up and down." Good job! Great question. Anymore, feel free to inquire. I am here for you.

erratum: recognize