The UK boss of Uber is to meet with the new leader of a trade union for the first time since a landmark court ruling on workers' rights.
Jamie Heywood and GMB's Gary Smith seek to end years of discord over the ride-hailing giant's business practices.
Uber recognised the union for the first time in May after the Supreme Court ruled its drivers should be classed as workers and entitled to better rights.
The bosses said "the exploitation" of all ride-hailing drivers must stop.
In a joint statement ahead of the meeting, Uber and GMB said an estimated 230,000 drivers were not receiving "their legal rights" from companies such as Bolt and Addison Lee.
However, Addison Lee boss Liam Griffin rejected the claims, saying drivers were "at the heart" of his business.
"We guarantee the drivers that work with us get the London Living Wage level of earnings, as opposed to only the National Minimum Wage paid by Uber," he said.
"Drivers working with Addison Lee also get access to a pension and holiday pay."
Bolt said record numbers continued to earn through Bolt "because they can take home more money".
"We don't take business advice from competitors motivated by their own agenda," it added.
Separately, the former Uber drivers James Farrar and Yaseen Aslam, who spearheaded the Supreme Court case against Uber, accused the ride hailing giant of running a "propaganda" campaign.
The App Drivers & Couriers Union (ADCU) leaders accused the firm of failing to implement the court's ruling by not paying drivers for waiting time, which they said made up 40% of drivers' working hours.
The BBC has approached Uber for a comment.
'Step towards fairer working'
Under the May deal between Uber and GMB, the union will be able to represent up to 70,000 Uber drivers across the UK in discussions over earnings, pensions, benefits and their health and wellbeing.
The agreement came after Uber lost the third and final stage of a five-year legal battle with drivers who claimed it had wrongly classified their employment status.
For years, Uber resisted calls to recognise unions, which had criticised the firm for not granting drivers basic rights such as sick pay or a minimum wage.
It argued it was a third-party booking agent, and its drivers were self-employed, but the Supreme Court ruled its drivers were workers, a category that means they are entitled to minimum legal, holiday and pension rights.
Mr Smith, GMB's general secretary, said the deal with Uber was the "first step towards a fairer working life for millions of people".
"It showed that when companies and trade unions work together, standards can be raised across these industries," he said
He said the Supreme Court ruling had set a precedent for all ride-hailing apps and urged others to follow.
"GMB and Uber today take the next step in our commitment to ending the exploitation of hundreds of thousands of ride-hailing app drivers," Mr Smith said.
Jamie Heywood, Uber's regional general manager for northern and eastern Europe, said he hoped working with GMB would "show the rest of the industry what can be achieved".
"We may not seem like obvious allies, but together we made history by striking a recognition agreement to improve workers' protections and, crucially, give drivers a stronger say in how Uber operates," he added.
Mr Heywood told the BBC that UK employment law had been "extremely ambiguous" on issues such as who was an employee and who was self-employed.
The Supreme Court had now "clarified" the law and given Uber the "mechanism" that it needed to act, he said.
When it was put to him that Uber had spent years exploiting that very ambiguity, he denied the charge, saying the firm was now able to "keep the flexibility that workers value, but also provide them with the protection that they deserve".
On the issue of whether Uber Eats riders would receive the same protection, Mr Heywood said he was "committed to providing good flexible work across both our Eats and our rides business".
However, he said the law was different for people in the Eats business, since the Court of Appeal had ruled in June that Deliveroo riders were self-employed and not employees of the company.
Employment experts and unions have heralded Uber's deal with GMB as a big step forward for workers' rights that would be felt across the gig economy.
However, the UK is the only country in which Uber has recognised a union, and it is still being challenged by drivers in other markets over similar issues.
Mr Griffin, chief executive of Addison Lee, said a decline in driver earnings and wellbeing across the industry was a "product of Uber's operating practices and predatory pricing model", which had led to a race to the bottom and threatened driver livelihoods.
Responding to the comments, Uber said its drivers were making "more than ever before driving with Uber, so the claim of a race to the bottom is totally untrue".