Opposition MPs agree that by passing laws, they will try to block Brexit without agreement in parliament.
Jeremy Corbyn convened a meeting between those who did not oppose any agreement.
A subsequent joint statement did not specify in detail how or when legislative attempts should be made, but Green MEP Caroline Lucas said this was the best way to stop a "career path" towards no deal.
The no-confidence vote against the government remained an option.
Britain is expected to leave the EU by 31
Ms Lucas said that "the legislative way forward" was "the surest way to extend Article 50 and abolish this deadline of 31 October".
Concerns were voiced over Labor leader Corbyn's proposal to demand a vote of no confidence in the government to stop a no-deal.
Under his plan, he would replace Mr Johnson as provisional Prime Minister, hold an early election, and campaign for another referendum.
However, the Liberal Democrats and some Tory MPs said they would not support a plan that led to Mr Corbyn becoming Prime Minister – not even temporarily.
Lib Dem leader Jo Swinson said after the meeting that a vote of no confidence remains "a last resort to enforce the will of Parliament, but the main proposal goes the way of legislation." 19659014] & # 39; productive & # 39;
The meeting was attended by the SNP, the Liberal Democrats, Change UK, Plaid Cymru and the Greens.
Anna Soubry, head of the Independent Group for Change, described the meeting as "excellent," while SNP's Ian Blackford said it was "positive and productive."
"Parliament must seize this opportunity to prevent Boris Johnson from ending democracy – and be ready to use all mechanisms to prevent a disaster-free disaster, including the implementation of laws as a priority," he said.
Adam Price, Chairman of Plaid Cymru, said his party was "committed to working with every other opposition party and doing everything in our power to prevent a catastrophic Brexit."
In a joint statement by the parties – sent by Labor – they agreed on the urgency of working together to find practical ways to prevent any business, including the ability to pass laws and issue a vote of no confidence.
Many of the opposition leaders – albeit not Labor – said that the focus of the meeting was on the first of these options – and indeed called for an extension of the Brexit process and sent Boris Johnson back to Brussels to speak out make a deal.
But how do you do that?
The first challenge to bring some conservative rebels on board because some in the Labor Party (namely Brexiteers) just do not support it.
But Boris Johnson still insists he can get a deal, it could well be the case that some Tory rebels, who are dissatisfied with the prospect of no deal, would be equally dissatisfied with plunging into something, that would undermine the Prime Minister at this stage.
So it's not safe at all. And anyway, even though he was forced to do something against his will, Mr. Johnson has the option of holding a poll instead.