The Tory leader spoke out as he clashed with SNP Westminster leader Ian Blackford during his first outing at Prime Minister's Questions in the Commons today.
"I'll tell you there's a reason, Mr Speaker, why the separatists in Scotland drone on and on about breaking up and smashing the oldest and most successful political union," Mr Johnson told MPs.
"The reason why they go on about it, that is to detract from their appalling domestic record.
"They have highest taxes anywhere in Europe, they have their educational standards falling for which they are responsible.
"And their signature policy is to return, after Brexit, to return Scotland to the European Union, complete with the euro and the full panoply of EU laws and, as I never tire of saying, surrendering Scottish fish just when they've been taken back by this country."
The Tory leader's attack n the SNP came as a new poll for the YouGov for the Times showed support for Scottish independence is now neck and neck with remaining in the UK. The SNP is also poised to win 51 of Scotland's 59 seats in a snap election.
Mr Blackford insisted that the SNP has a "majority" in Scotland.
"The people of Scotland voted to Remain in the European Union - we're not going to be dragged out against our will by the Prime Minister," he said.
"The Prime Minister also mustn't be paying attention to the polls this morning which shows that the SNP is polling to win a majority in Scotland once again, with the Tories in retreat."
"The Prime Minister is playing a game of bluff and bluster - he doesn't care about stopping a No Deal Brexit," Mr Blackford added.
"His strategy, as his lead adviser put it, is a sham. This isn't the Parliament versus the people, it is a Parliament standing up for the people.
"The people did not vote for a No Deal Brexit, this Prime Minister is robbing the people of power, handing control to the Leave campaign, a cult now running Number 10.
"Once again I ask the Prime Minister, are you a dictator or are you a democrat? Will the Prime Minister accept the legislation so that no deal can be avoided and let us vote for an election so that the people can truly decide."