An animal euthanization assembly provides a method for humanely anesthetizing and euthanizing animals using small but effective single doses of agents dispersed from a single one use container. The assembly includes a box having a bottom wall and a perimeter wall coupled to and extending upwardly from the bottom wall defining an interior space of the box. A lid selectively couples to the box wherein the interior space is enclosed. A valve is coupled to the box. A canister has a dispensing nozzle selectively engageable to the valve wherein contents of the canister are dispensed into the interior space of the box when the dispensing nozzle is engaged to the valve. An anesthetizing agent and a euthanizing agent are dispensed from the canister when the dispensing nozzle is engaged to the valve.