March 19, 2019
In a surprise ruling, he said he would not allow a third "meaningful vote" in the coming days on "substantially the same" motion as MPs rejected last week.
With 11 days to go before the UK is due to leave the EU, ministers have warned of a looming "constitutional crisis".
The UK is currently due to leave the EU on 29 March.
Theresa May has negotiated the withdrawal deal with the EU but it must also be agreed by MPs.
They have voted against it twice, and the government has been considering a third attempt to get it through Parliament.
Mr Bercow cited a convention dating back to 1604 that a defeated motion could not be brought back in the same form during the course of a parliamentary session.
He said the second vote on the prime minister's deal last week was "in order" as it was substantially different to the first, but any further votes must pass the "test" he set out to be allowed.