Our 24yr old daughter lives with us full time. She had a great full time job till May 2022. She lost her job, We supported her 100% the rest of the year. Who claims her?

"She had a great full time job till May 2022."

If your daughter earned more than $4400 in 2022 she cannot be claimed as anyone else's dependent.  She is too old to be a qualified child, and had too much income to be a qualified relative.

If her gross income in 2022 was $4,400 or more then no one can claim her as a dependent.  She needs to file her own tax return.

In order for you to claim her, she can't have earned more than $4,400 in 2022.

Qualifying Relative

You can claim a child, relative, friend, fiancé (etc.) as a dependent on your 2022 taxes as long as they meet all of the following requirements :

• You provided more than half of their financial support. More info
• They made less than $4,400 in gross income during 2022 unless they are a qualifying child.
• They live with you or they are related to you. (Your relative must live at your residence all year or be on the list of “relatives who do not live with you” in Publication 501.) 
• They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren't (or won't be) claimed as a dependent by someone else.
• They aren’t filing a joint return with their spouse.
• You are not being claimed as a dependent on someone else's return.