Neutralize urine odor in a mattress with a vinegar blot and an overnight baking soda draw, no soaking required.
Strip the bedding and press a stack of clean dry towels firmly onto a fresh spot to wick up as much liquid as possible. Stand on the towel if needed. Don't rub — that pushes urine deeper into the foam.
Mix 1 part white vinegar to 1 part water in a spray bottle and mist the stained area until lightly damp, not soaked. Vinegar's acidity neutralizes the alkaline salts in urine that cause the lingering smell. Blot again with a dry towel.
Once the area is just damp, sprinkle a thick, even layer of baking soda over the whole spot. Leave it 8 hours or overnight — it draws out remaining moisture and odor as it sits. Crack a window or run a fan to speed drying.
Vacuum up all the baking soda with an upholstery attachment. If any smell remains, repeat the vinegar-and-baking-soda cycle. Let the mattress air-dry fully before putting sheets back on to prevent mildew.