Longfield wants to see loot boxes included in gambling legislation after a new report, Gaming the System, was published today.
The report examines the way developers and publishers are increasingly finding ways to encourage users to spend more money via potentially exploitative systems.
The Commission spoke with several children who feel they are developing a gambling habit, including a 14-year-old who said he "never gets anything out of it."
Longfield said: "Children have told us they worry they are gambling when they buy loot boxes and it’s clear some children are spending hundreds of pounds chasing their losses.
"I want the Government to classify loot boxes in games like Fifa as a form of gambling."
The Commissioner’s call comes weeks after the Department of Digital, Culture, Media and Sport published its own report detailing the findings of a nine-month inquiry, based on evidence from developers, academics and trade bodies.