Officially, Ron Dennis-led McLaren has said that Boullier, who is just 40, will work "with" chief operating officer Jonathan Neale and other "senior management", and report to the so-far unnamed new McLaren F1 chief executive.
But with Martin Whitmarsh expected to leave McLaren altogether, Boullier said in Bahrain that he has effectively become the new team principal.
"Yes," he told Britain's Sky, "it is definitely a team principal role on track and let's say that off track I have to focus more on the performance of the team."
On the other hand, Boullier said the old concept of a single team boss is now defunct.
"Time has changed and moved forward and you cannot have a team principal acting in the sole role today," he insisted.
"I think teams are now getting bigger and you have to share the responsibilities of the organisation to make sure you make the best of it."