The probe will seek evidence about the benefits and problems caused by platforms.
The House of Lords EU Committee has launched an investigation to identify the fairness and transparency of online platforms such as Google, Amazon and Uber.
Issues like data use, market dominance, and relations among platforms and their suppliers, including SMEs, will be the main focus of the investigation.
Evidence will be sought on the benefits and problems caused by online platforms for consumers and businesses.
The social and political issues raised by online platforms will also be considered. The committee will ask consumers if the EU online marketplace is good for new start-ups to expand their businesses and for new platforms to develop.
Written evidence on the issue should be sent to the committee by 16 October.
Chair of the Committee Lord Whitty said: "Online platforms are playing an ever more central role in society and the economy, and the question of whether regulatory change is needed is one of the most important aspects of the Commission’s Digital Single Market Strategy.
"Our inquiry will accordingly take stock of the benefits and the problems that platforms bring, before trying to establish whether EU level regulation could solve them.
"The inquiry is a timely one, taking place against the background of a new EU Commission drive to stimulate e-commerce and its own consultation on online platforms, and we look forward to receiving contributions to our inquiry. We particularly want to hear the views of small businesses and consumers."