The deal will close in the coming days, according to Tesla. In August, Tesla gained antitrust approval for the $2.6 billion deal.
"We would like to thank our shareholders for continuing to support our vision for the future. We look forward to showing the world what Tesla and SolarCity can achieve together," wrote Tesla in a statement on its blog.
Tesla announced plans to buy the solar panel maker in August as part of its push to become a renewable-energy products company. Last month, Tesla and SolarCity unveiled a Solar Roof made of solar panels integrated within glass roof tiles.
Some investors pushed back at the deal because of Tesla CEO Elon Musk's connection to SolarCity. In addition to his role with Tesla, Musk is also the chairman and largest individual shareholder of the solar company. Lyndon Rive, CEO of SolarCity, is also Musk's cousin.
Tesla called the merger "the first ever opportunity to generate, store, and consume energy entirely sustainably, through a suite of integrated products that add aesthetics and function while reducing cost," in a post to investors on its website.
Tesla said on Tuesday the SolarCity merger will add $500 million in cash to its balance sheet over the next three years and over $1 billion to revenue next year.
The largest owner of both companies, Musk, owns 21 percent of Tesla and 22 percent of SolarCity.