The purpose of the rules is to prevent Internet providers from speeding up access to websites that pay special fees, or to their own sites. There is also concern that without the rules, Internet providers could slow down or block their competitors' sites.
The supporters of the rules say all websites should be treated equally, whether they are large corporate services or small personal blogs.
In its lawsuit, Verizon argued that the FCC lacked the legal authority to enact the rules and that the agency acted without sufficient evidence to suggest the rules were necessary.
The company also claimed that the rules violate its First Amendment right to free speech.
But in Thursday's filing, the technology companies, which united to form the Open Internet Coalition, argued that the rules fall within the FCC's authority to "encourage the deployment" of broadband Internet services.
The companies argued that increasing demand for data-heavy Internet content, such as steaming movies and online video chatting, drives investment in broadband.
The brief argued that many companies that provide those data-heavy Internet services "have based decisions to embark on significant investments precisely upon the premise of non-discriminatory access to content."
"If demand for the Internet were to stop growing or to grow more slowly, this would likely deter investment in new conduits to the Internet," they wrote.
The companies said the order has already spurred investments in wireless and wireline broadband, making it "one of the levers propelling the U.S. economy out of the still-lingering economic crisis."
They argued that if Internet providers could act as gatekeepers to web services, innovative startups would be "marginalized, stifled, endangered, or rendered extinct for failure to find funding."
The coalition also dismissed Verizon's claim that the rules violate its First Amendment rights, arguing that the rules actually facilitate free speech.
They argued that as an Internet provider, Verizon only transmits the speech of others and is not expressing any message of its own.
"The First Amendment is not the Open Internet Rules’ victim; it is their beneficiary," the companies wrote.
Consumer advocacy group Public Knowledge joined the companies in filing the brief.
Also on Thursday, the Center for Democracy and Technology, legal scholars, venture capitalists, former FCC Chairman Reed Hundt and former FCC Commissioner Michael Copps also filed briefs defending the rules.
The D.C. Court of Appeals, which is hearing Verizon's challenge, already ruled against the FCC when it tried to enforce the principle of net neutrality against Comcast in 2010. That setback led the FCC to enact its current regulations later that year.