"#KickstarterUnited has now been certified by the [National Labor Relations Board]: We Are A Union!!!" the union wrote on Twitter.
"We'll begin discussing our priorities and forming an inclusive and representative bargaining committee for everyone at Kickstarter so that we can ... bargain our first contract!" the union wrote.
The union will be under the Office and Professional Employees International Union.
Kickstarter employees took their union push public in March 2019. There have been unionization efforts at other tech companies, including Microsoft. Meanwhile, Amazon employees have threatened walkouts to get Amazon CEO Jeff Bezos to pledge the company will take dramatic steps to fight climate change.
Union membership dipped slightly last year despite Americans' growing approval of labor unions that nearly reached a 50-year high.
The membership rate fell 0.2 percentage points to 10.3 percent in 2019, the Bureau of Labor Statistics said last month.
That's about half the rate in 1983, when the Bureau of Labor Statistics started keeping comparable union data. Then, 20.1 percent of wage and salary workers were union members, which was about 17.7 million people.