Is it grammatically correct to say I’m good?

Summary: I’m good is correct, because am is a linking verb, taking an adjectival predicate, and good is that adjective. I’m good means that one is fine, in good spirits, etc.

What is the meaning of I am good?

1. I am in a state of generally satisfactory health or wellbeing. A: “How are you, Tom?” B: “I’m good, thanks.” 2. I am not hurt or sick; I am all right.