A grand jury in Henry County, GA ruled ... there was not enough evidence against Waka to warrant a trial for the drug charges filed against him -- possession of a controlled substance and possession of weed measuring less than an ounce.
Three other charges stemming from the raid were dropped before the case went in front of the grand jury.
TMZ broke the story ... cops raided Waka's Georgia home back in December and arrested several people -- including fellow rapper Gucci Mane. Waka was not home during the raid.
So far, no comment from Waka's people.