Theresa May's hopes of winning backing for her Brexit deal have been hit with a fresh blow after Mr Gyimah handed in his resignation.
Writing in The Daily Telegraph, the Tory MP for East Surrey told how he could not support the "naive" agreement with Brussels which was "not in the national interest".
The Remainer is the seventh minister to resign from the Government since Mrs May unveiled the draft Withdrawal Agreement.
In his article, Mr Gyimah said that if MPs were to support the agreement it would "set ourselves up for failure" by surrendering "our voice, our vote and our veto".
"Britain will end up worse off, transformed from rule makers into rule takers.
"It is a democratic deficit and a loss of sovereignty the public will rightly never accept," he said.
The minister also announced his resignation on Twitter, saying: “After careful reflection, I will not be supporting the Government on the EU Withdrawl Agreement.
“As such, I have tended my resignation as Universities and Science Minister.”
“Britain will end up worse off, transformed from rule makers into rule takers”
His departure underlines the uphill task the Prime Minister faces if she is to win the crunch vote in the Commons on the deal on December 11.
He joins several other ministers who have handed in their resignation letters to the Prime Minister.
Most notable among them have been former foreign secretary Boris Johnson, his brother ex-Transport Minister Jo Johnson and previous Brexit Secretary Dominic Raab.
The resignations have highlighted the unpopulaity of May's deal with the EU, raising questions over whether she will be over to get the Withdrawl Agreement passed.