Answer first: the best Montessori activities for a 1 year old are simple, hands-on, and built around what a new walker loves, putting things in and taking them out, moving objects around, and imitating you. Think object permanence boxes, simple stacking and nesting, a basket of safe household objects to explore, posting toys (dropping balls or coins through a slot), and letting them "help" with real tasks. At this age you need almost no special toys. A few open-ended objects and permission to explore do the most.
One-year-olds are in a magical, messy window: newly mobile, endlessly curious, and driven to touch everything. Montessori activities for this age are not fancy, they simply channel what a 1 year old naturally wants to do. Here are the ones that actually land.
In-and-out and posting
The number-one obsession at this age is putting objects into containers and taking them back out. Lean all the way in. A basket and some balls, a box with a slot to "post" objects through, cups to fill and dump. An object permanence box (where a ball disappears and reappears) is a Montessori classic for exactly this reason. It looks like nothing; to a 1 year old it is fascinating and it builds hand control and early problem-solving.
Stacking and nesting
Simple stacking cups, nesting bowls, or a few chunky blocks give a 1 year old cause-and-effect, coordination, and the thrill of knocking it all down. Keep it simple, a handful of pieces, not an elaborate set. The classic simple wooden and open-ended toys shine here.
A treasure basket of real objects
Fill a basket with safe, interesting household objects of different textures and weights, a wooden spoon, a metal cup, a fabric scrap, a large pinecone. Let your child explore them freely. This "treasure basket" is pure sensory learning and costs nothing. Just make sure every item passes the no-choking-hazard test (see safe-toy basics).
Movement and gross motor
New walkers need to move. Give them safe things to cruise along, push (a weighted push wagon or a sturdy box), and climb over. Low cushions and tunnels turn the floor into a gross-motor gym. Movement at this age is learning.
Letting them "help"
A 1 year old loves to imitate you. Let them wipe a surface with a cloth, drop laundry in a basket, or hand you items while you cook. It is real practical-life work at the earliest level, and they take it seriously. (More in Montessori parenting at home.)
Keep it simple
The theme at 12 to 18 months is less is more. A few open-ended objects, a safe space to move, and your willingness to let them explore and imitate beat any expensive toy. Rotate a small selection so it stays fresh, and follow whatever they are drawn to that week.
Next stage up? See Montessori activities for a 2 year old. For choosing toys that suit this age, see what baby sensory toys are.