CNBC had reported Friday that a deal, valued at $50 a share, was in the works.
Snyder's stock jumped 6.7 percent in Monday's premarket to $49.95 a share.
The deal underscores the drive for food industry consolidation as traditional food companies watch their sales drop and struggle to create growth or innovation on their own. It points to the opportunity they see in snacks, appealing to the increasing number of people who eat and shop on the go.
Campbell's stock, before news of its plans to acquire Snyder's broke, was down roughly 18 percent during the past year. Sales in its America's simple meals and beverages segment, which includes soup and V8 beverages, has declined on an annual basis since 2015. Sales in its global biscuits and snacks division, which include Pepperidge Farm Goldfish and Milano cookies, were up 3 percent in the most recent quarter.
Adding Snyder's snack brands like Diamond Foods and Pop Secret popcorn will broaden Campbell's snack business and create a stronger foothold into convenience stores.
"This acquisition will dramatically transform Campbell, shifting our center of gravity and further diversifying our portfolio into the faster-growing snacking category," CEO Denise Morrison said in a statement Monday morning.
Campbell's baked snacks generated roughly 31 percent of Campbell's sales in fiscal 2017. Adding Snyder's-Lance's snack brands will bring that proportion up to roughly 46 percent of Campbell's annual net sales. Campbell's soup brands — including its recent acquisition of Pacific Food organic soup — will now represent about 27 percent of the company's annual net sales.
The deal is the boldest in a series of smaller steps to move beyond its core soup business, as Morrison heads into her seventh year in the job.
Campbell acquired dressing, beverage and vegetable company Bolthouse Farms in 2012 for $1.55 billion. This month, it completed its $700 million acquisition of Pacific Foods. Last year, it joined the ballooning number of consumer packaged giants to launch a venture unit in hopes of keeping closer tabs on innovation.
Pressure on Big Food to do larger deals that can make a more immediate impact has heightened over the past year. Beyond slowing sales, food companies are working with increasingly punishing retailers that are under their own pressure as shoppers pick up their food staples at convenience stores and, increasingly, Amazon. To stay relevant, grocers have focused on fresh food to bring shoppers into their stores.