"Let me say unequivocally, President Trump and his administration made the right decision on blocking Broadcom from taking over Qualcomm," he said from the Senate floor Tuesday.
The Senate minority leader's comments come after President Donald Trump ordered the companies to abandon the proposal and barred Broadcom's 15 proposed candidates for Qualcomm's board from standing for election. Trump said he had "credible evidence" that the deal had the potential to threaten the national security of the United States.
Broadcom has repeatedly said that it disagrees that its bid to buy Qualcomm would present any kind of national security concern. The Singapore-based company had been optimistic that its plan to move its headquarters to the U.S. could save the deal.
Schumer called this a "happy moment" and urged greater scrutiny of foreign entities that seek controlling stakes in American companies.
In particular, the New York Democrat called out China, saying the country has been "very smart" about trade. Schumer said that Beijing is always looking for opportunities to "steal" American technology and innovation.
"When China attempts to steal our best technology by buying American companies, whether it's robotics or AI or chips — like here in Qualcomm — we ought to block it," Schumer said.
The Treasury Department's Committee on Foreign Investment in the United States had raised concerns about Broadcom's pursuit, which was unprecedented for a deal that hadn't been formally announced or agreed to.
One of the committee's concerns had been how the transaction could stymie U.S. progress in developing 5G wireless network technology. In its March 5 letter, CFIUS said the San Diego-based Qualcomm is a "trusted" player in the nation's telecommunications infrastructure.
"Having a well-known and trusted company hold the dominant role that Qualcomm does in the U.S. telecommunications infrastructure provides significant confidence in the integrity of such infrastructure as it relates to national security," the Treasury Department wrote to lawyers involved in the proposed deal.
With Broadcom's reputation for slashing research spending, some had feared the resulting company would be less competitive in the race against China to dominate 5G innovation and development.
The Treasury Department said, "China would likely compete robustly to fill any void left by Qualcomm as a result of this hostile takeover." That "would have substantial negative national security consequences for the United States."
— CNBC's David Faber and Alex Sherman contributed to this report.