TORONTO — Executives of Restaurant Brands International, Inc. had two menu item success stories to talk about when giving third-quarter financial results. First, Burger King’s U.S. comparable sales jumped 5% in the quarter behind the launch of the Impossible Whopper, a plant-based burger. Second, Popeyes Louisiana Kitchen is bringing back the chicken sandwich.

Restaurant Brands International said net income totaled $351 million, or 76c per share on the common stock, in the quarter ended Sept. 30, which was up 40% from $250 million, or 53c per share, in the previous year’s third quarter. Total revenues rose 6% to $1,458 million from $1,375 million in the previous year’s third quarter.

System-wide sales for Burger King grew 11% in the quarter with comparable sales growth at 4.8%. Within the United States, the launch of the Impossible Whopper drove sales growth of 6% and comparable sales growth of 5%.

“The Impossible Whopper is a huge hit with our guests and has quickly become one of the most successful product launches in Burger King’s history,” said José E. Cil, chief executive officer of Restaurant Brands International, in an Oct. 28 earnings call. “What’s especially exciting is that the sales of the Impossible Whopper have been highly incremental and have attracted new types of guests into our restaurants.

“It’s really been something to see as I visited stores across the country, and our team has been getting a lot of questions as to just who this guest is that’s coming in for the Impossible Whopper. We’ve done a lot of research and found that the appeal is quite broad-based across several types of consumers. We see a lot of millennial and Gen Z customers who tend to really connect with the message around sustainability. We also see older guests that perhaps used to come to Burger King but haven’t visited in a while.”

Burger King teamed up with Impossible Foods, Redwood City, Calif., to create the Impossible Whopper, which launched nationwide in August. Burger King is expanding its plant-based platform outside of the United States, Mr. Cil said.

“We recently launched plant-based beef and plant-based chicken products in Sweden, the Rebel Whopper and the Rebel Chicken King, and are developing great new products for markets in Latin America and Asia as well,” he said.

Burger King’s sales increased by 15% in international businesses. Burger King has more than doubled the number of its restaurants outside the United States to almost 11,000, which is up from about 4,700 in 2010, Mr. Cil said.

Popeyes Louisiana Chicken in the third quarter achieved systemwide sales growth of 16% and comparable sales growth of 10%. The limited-time chicken sandwich originally launched in August.

“While the chicken sandwich was an important component of overall sales growth in Q3, it’s important to remember that it was only in stores nationally for about two weeks,” Mr. Cil said. “The demand was so overwhelming that the supply we secured to support an aggressive sales forecast over several months ran out in approximately 14 days.”

The chicken sandwich lifted other parts of the Popeyes business, including chicken, tenders, beverages and desserts, he said. Popeyes plans to bring back the chicken sandwich on Nov. 3.

“Our teams and franchise partners have been working around the clock over the past two months to make sure we’re ready to relaunch,” Mr. Cil said.

Still, Restaurant Brands International’s stock price on the New York Stock Exchange closed at $65.86 per share on Oct. 28, which was down from a close of $68.45 on Oct. 25. Tim Hortons, another restaurant chain owned by Restaurant Brands International, did not fare as well in the quarter.  Systemwide sales dipped 0.1%, and comparable sales were down 1.4%.

“In Canada, softness in comparable sales reflected a tough year-over-year comparison as we lapped the launch of ‘Breakfast Anytime’ in 2018,” Mr. Cil said. “In particular, we saw softness in our lunch food offering, where we continued to see a gap in sales of our sandwiches and wraps.”

He said management will focus on four areas for Tim Hortons: coffee leadership, food quality and innovation, guest experience, and community connection.

For the first nine months of the fiscal year, Restaurant Brands International posted net income of $854 million, or $1.85 per share on the common stock, which was up 1.3% from $843 million, or $1.81 per share, in the same time of the previous year. Nine-month total revenues rose 3.8% to $4,124 million from $3,972 million.