A tri-fold bag for containment of items while walking a pet, the tri-fold bag including a collapsible main compartment section made from a water-resistant flexible material having an opening opposite a base with drain holes, and foldable along its length. A cover flap is foldable over the opening for enclosing the main compartment section when open, and foldable over the tri-fold closed configuration. Fastener straps provide for attaching a shoulder strap or a leash to the tri-fold bag during the pet walk. The tri-fold bag includes a plurality of easily accessible secondary compartments for storage of personal items while walking the pet.
