Motorola Mobility’s shareholders approved Google’s $12.5 billion buyout deal at a special meeting on Thursday, clearing a key hurdle for the closing of the deal.

About 99 percent of the shares voted at the meeting were in favor of the merger. Those shares represented about 74 percent of Motorola Mobility’s total outstanding common stock as of Oct. 11, the record date for the meeting.

“We are pleased and gratified by the strong support we have received from our stockholders,” Motorola Mobility CEO Sanjay Jha said in a statement. “We look forward to working with Google to realize the significant value this combination will bring to our stockholders and all the new opportunities it will provide our dedicated employees, customers, and partners.”

Google said when it announced the merger in August it expected to close the deal by the end of this year or early 2012. In yesterday’s announcement, the company said the acquisition would be complete towards the latter end of its estimate, and it “currently believes that the close is expected to occur in early 2012.”

Google’s merger with Motorola Mobility will give it control over a key manufacturer of smartphones running its Android operating system. Google has pledged to run Motorola Mobility as a separate company and leave the Android ecosystem unchanged, but the acquisition prompted initial concerns that Google would favor Motorola over other licensees of the open-source operating system such as Samsung and HTC.

Motorola’s portfolio of 17,000 patents played a key role in the deal. Google needed a way to bolster its intellectual property holdings to fend off patent lawsuits after placing failed bids on patent portfolios held by Novell and Nortel. Google claims that Apple and Microsoft are using their patents to wage a “hostile, organized campaign” against Android by burdening the platform with costly licensing fees.