My boyfriend recently had a blood and urine test to check his health. Can this test validate if he has an STD or sti? Everything came out negative.

Depends. It depends on what test(s) were ordered--will not find what is not looked for. Stds are tested for with either blood or urine specimen (depending on which std), so is possible. Need to ask him if he knows which tests were done, or he will need to contact his provider for clarification.