The European Commission is investigating whether Nike, Universal Studios and Japan's Sanrio are preventing traders from selling products across EU borders and online.
EU Competition Commissioner Margrethe Vestager said the probe would "examine whether the licensing and distribution practices of these three companies may be denying consumers access to wider choice and better deals".
Sports giant Nike, film-maker Universal and Sanrio, owner of Hello Kitty, license rights to some major world brands.
They control the use of images or text applied to merchandise such as clothes, shoes, bags or toys to make them more attractive, often to children.
The commission said it wants to find out whether they breached EU competition rules by restricting traders from selling licensed merchandise cross-border and online.
The three could face fines if found guilty.