LEGO bricks are made from various types of plastic materials, each with different characteristics depending on how they are intended to be used, but all share the same high standards of quality and safety. The most common type of plastic used to make LEGO bricks is ABS (Acrylonitrile Butadiene Styrene), which is a hard plastic that is very scratch-resistant and optimal for achieving the perfect clutch power. HIPS (High Impact Polystyrene) is used to make LEGO baseplates, while PA (Polyamide) is used for elements that need to be tough and able to interact with each other, such as gearwheels and different connectors. PP (Polypropylene) is used for LEGO elements that have few functionalities but often add that extra spark to a build, such as a ninja sword, handcuffs, and a LEGO storage box. TPU (Thermoplastic Polyurethane) is used for making LEGO elements that can be bent and twisted without separating, such as the LEGO DOTS bracelets, straps for LEGO VIDIYO™ BeatBoxes, and the tails and ears of some animal figures.

Historically and currently, LEGO bricks are made with a variety of materials depending on the use case. From 1949 until 1963, cellulose acetate was the polymer used. However, since 1963, LEGO pieces have been manufactured from ABS. In 2018, LEGO announced that it would be using bio-derived polyethylene to make its botanical elements, such as leaves, bushes, and trees. In 2020, the company announced that it would cease packaging its products in single-use plastic. LEGO has also been working on using more sustainable raw materials for its products, with a goal of using fully sustainable materials by 2030.