Benchmark is suing Kalanick over allegations of "fraud, breaches of fiduciary duty, and breaches of contractual obligation," according to a complaint filed in Delaware Chancery Court. Axios was first to report on the lawsuit.
The venture capital firm alleges Kalanick "fraudulently" obtained the power in 2016 to name three additional members to the company's board of directors. After Kalanick resigned in June, he appointed himself to one of those seats.
Benchmark has a 20 percent stake in the company's voting rights, according to the lawsuit. The privately-held Uber is believed to be worth approximately $70 billion.
A representative for Kalanick said the lawsuit is "completely without merit and riddled with lies and false allegations."
"This is continued evidence of Benchmark acting in its own best interests contrary to the interests of Uber, its employees and its other shareholders," the representative said. "Benchmark's lawsuit is a transparent attempt to deprive Travis Kalanick of his rights as a founder and shareholder and to silence his voice regarding the management of the company he helped create. Travis will continue to act in the interests of Uber and all of its stakeholders and is confident that these entirely baseless claims will be rejected.”
A representative for Uber declined to comment on the lawsuit. Benchmark could not immediately be reached for comment, though the firm has declined comment to other outlets.
Uber has dealt with several problems this year, including issues of gender bias and harassment in the workplace and a trade-secret-theft lawsuit from self-driving car company Waymo. A tape of Kalanick arguing with an Uber driver over falling fares was also released in February, prompting the CEO to apologize and admit that he needs leadership help.
Benchmark general partner Bill Gurley, a former Uber board member who helped lead the effort to oust Kalanick, struck a diplomatic tone in June about the resignation. The former Kalanick confidant was said to be one of the key people who urged for him to resign.
There will be many pages in the history books devoted to @travisk - very few entrepreneurs have had such a lasting impact on the world.
While he may be out as CEO, reports have been swirling that Kalanick may have been plotting a return to his old position. On Monday, after hearing "confusion" around the CEO search process, Uber co-founder and board member Garrett Camp said that won't be the case.
"It’s time for a new chapter, and the right leader for our next phase of growth," he told employees. "Despite rumors I’m sure you’ve seen in the news, Travis is not returning as CEO. We are committed to hiring a new world-class CEO to lead Uber."
Yet another sign Uber is looking to move on to its next phase: Ryan Graves, an early Uber employee and the only other person to serve as the company's chief executive, resigned on Thursday as senior vice president of global operations. Graves said he plans to focus on his role as a member of the board, which includes choosing a new CEO.
"In some ways my focus going forward will not actually change very much — it remains all about people, and it’s clear to me the stability of our board of directors, the selection of our new CEO, and the empowerment of our management team is what is needed most," he said.
Alyssa Newcomb is an NBC News contributor who writes about business and technology.