Following talks with the PM, Sinn Fein insisted that a no-deal exit would be "a very dangerous course" of action for the people of Ireland.
Party leader Mary Lou McDonald criticised Mr Johnson's impartiality on the issue of the Northern Ireland backstop - after he had a private dinner with the DUP leader Arlene Foster on Tuesday evening.
Ms McDonald said: "Boris Johnson's first priority coming to Ireland is his interests, Tory interests, British interests as he sees them and it seems to me that he is quite complacent at the idea of Ireland becoming collateral damage."
The DUP is currently helping to prop up the Tory government in parliament and their MP Jim Shannon told Premier's News Hour Mr Johnson was not being unfair: "He has made it his business to speak to every political party in Northern Ireland, he is genuinely seeking out their opinions so that he himself will be better versed in what the critical and crucial issues are in Northern Ireland."
Jim Shannon is certain that Mr Johnson's strong leadership style will be beneficial for EU negotiations and the future of Northern Ireland.
"I have confidence in the prime minister, that he will have the ability first of all, the interest number two, and perhaps maybe that wee bit of charisma that's needed from a prime minister.
"Let's give the prime minister a chance to negotiate a withdrawal agreement from the EU that's acceptable.
"I think he can do that."
He went on to say that Boris Johnson is proving to be a man of his word and that his clear negotiation stance of "no withdrawal agreement, no deal" is one that the UK has needed from the start.
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