A seat assembly includes a seat frame and a seat cushion coupled to the seat frame. The seat frame includes a seatback frame, a base frame coupled to the seatback frame, a first armrest frame coupled to the seatback frame, and a second armrest frame coupled to the seatback frame. The seat cushion covers the seat frame and is spaced apart from the seat frame to define a cavity therebetween. The seat assembly further includes an airbag coupled between the seat frame and the seat cushion. The airbag has a stowed position and a deployed position. In the stowed position, the airbag is disposed in the cavity between the seat frame and the seat cushion. In the deployed position, the airbag is partly disposed outside the cavity between the seat frame and the seat cushion to absorb energy.