Moving my brother from a nursing home in Mississippi. How do I go about signing him up for Medicaid here in Kentucky?

Call Kentucky Medicaid. There may be a reciprocity agreement in place between Mississippi and Kentucky. That is the case with some other states.

Lovemuffinluv: Retain an elder law attorney.

Because policies vary from state to state and you can't transfer Medicaid from one state to another, you're going to be better off to ask an elder atty to help you out. Mississippi may allow him to have more money in his bank account than Kentucky allows, for example. More than likely the expense of his move could be used out of his bank account if he has too much to lower it to correct balance amount.

You might even talk to a NH you're interested in to find out if they have bed now and can help you start the application process. Basically, you're asking a NH to let him come in and pend the approval for payment. Ex, if they said he can come on April 1 into the facility, even though it might take a couple months for approval, state Medicaid would pay retroactively back to the date of the application. NH may ask family to pay the bill until approval, but should reimburse you once it kicks in.

You need guidance from the pros on this: Atty, Medicaid office, etc

I moved my mom from her home in Ohio to a NH here in Kentucky. I did not change her address until after I had applied for Medicaid in KY. I did hire an elder law attorney to help.
From what I've gone through so far (still pending) Kentucky is harder to get approval than other states (Ohio).
Mom also has Medicare, Humana. I haven't done anything at all to change this. My attorney has not told me to change anything there yet and mom is still paying for Humana.

Yes, you need to talk to Medicaid in Kentucky before you move him. He may have to be in the State for a time to establish residency. Medicaid does not go from State to State. Either do Medicare Advantages or supplimentals so you need to check with those insurances to see if they write policies in Kentucky.

Your local Social Security agency should be able to help him.

You need to move him first then establish residency with mail that has his new address

Go to your county social services office or perhaps the NH social worker can help with the application.