Smith will lead a delegation of 18 senior executives, including Microsoft Gaming Chief Executive Officer Phil Spencer, while Activision will be represented by its CEO Robert Kotick according to a European Commission document seen by Reuters.
Alphabet's (GOOGL.O) Google and chip designer and computing firm Nvidia Corp (NVDA.O), which has a gaming business, will also be taking part in the hearing, the EU document showed.
"The European Commission asked for our views in the course of their inquiries into this issue.
We will continue to cooperate in any processes, when requested, to ensure all views are considered," a Google spokesperson said.
The European Games Developer Federation (EGDF), which has said the deal will allow Microsoft to challenge Apple (AAPL.O), Google and Tencent, is one of the participants.