A wheeled walker convertible to a transport chair. The walker has a strap-type backrest that is pivotally attached to the upper end of the handlebars. The backrest can be placed in a forward position when the apparatus is used as a walker and the user wishes to rest in a rearward facing sitting position and in a rearward position when the apparatus is used as a transport chair and the user sits in a forward facing position and is propelled by a care-giver. A novel braking system locates the brake actuating linkage inside the leg and handlebar members and provides accommodates extension height adjustment of the handlebars. A brake lever system providing a linear pull non-cable brake actuation is also disclosed.