Goodell said it's up to the Raiders to decide whether they want to try to build a stadium in Oakland or share the facility at Levi's Stadium with the 49ers -- an idea Niners CEO Jed York never has dismissed.
Raiders owner Mark Davis has said he doesn't want to be a renter in the 49ers' facility, which is now fitted with red seats and posters of past and present San Francisco greats.
"They have to make that determination, whether they're in a new stadium in Oakland or whether they feel that it's best to join this stadium," Goodell said, according to the Bay Area Sports Guy, who tweeted the commissioner's remarks. "We're working on that, and that's one of the decisions they'll have to make."
The Raiders are in the final year of their lease at the Coliseum and are interested in building a new stadium at the site.
The Coliseum has hosted MLB's Athletics since 1968 but has had sewage and lighting problems. The Oakland City Council approved a 10-year lease to keep the team in town Wednesday but with several modifications that left it "disappointed," according to A's team president Mike Crowley.
The O.co Coliseum is the lone facility shared by a Major League Baseball club and a team in the National Football League. The Raiders reportedly have been in talks to have the aging structure demolished in 2015 to make room for a new home.
If the Raiders and 49ers were to share Levi's Stadium, they would become the second pair of NFL teams to share a home, joining the Jets and Giants, who both play at MetLife Stadium in East Rutherford, New Jersey.
The Levi's Stadium ceremony marked the official opening of the 49ers' $1.2 billion home in Santa Clara. Goodell, 49ers coach Jim Harbaugh, linebacker Patrick Willis and left tackle Joe Staley joined York and others on stage to cut the ribbons.
They used oversized red scissors with gold-colored blades in keeping with team colors. Hard hat-wearing construction workers lined the steps in fluorescent yellow jackets as team employees cheered and a fog horn blared.
"This is a long time in the making," York said.
Goodell called it a milestone for the league.
The 49ers' new home will hold about 68,500 fans and has the ability to expand to 75,000 for Super Bowl 50 in February 2016. The facility features 165 luxury suites, 9,000 club seats and even a green rooftop deck that includes solar panels and harvested herbs for on-site food preparation.
Free Wi-Fi will be available at the stadium, and a smartphone application will allow fans to have food delivered to any seat and check waiting lines at concession stands and bathrooms.
"The stadium reflects the greatness of the region, the technology and the innovation," Goodell said.
The seats in the lower bowl will hold some 45,000, or two-thirds of stadium capacity, and will be the largest first level in the NFL. All club levels look out to the field in one direction and the surrounding valley and mountains in another. It's 35 rows up to the first club seating area, while Row 1 of the stadium is about 10 feet off the field.
The only lingering stadium concerns from most 49ers fans involve the traffic in an already congested area and rising ticket prices. And, of course, some are still bitter about the team leaving San Francisco, where the team tried and failed for decades to get a new stadium.
Levi's Stadium, steps away from the 49ers' practice facility, is about 45 miles south of downtown San Francisco -- the longest distance any team in the league has to the city that bears its name. The 49ers had played in San Francisco since their establishment in 1946, including the past 43 years at Candlestick Park, where the team won all five of its Super Bowl titles.
The whipping wind and cold air from the city's famous fog made conditions constantly change at Candlestick, which is set to be demolished. That's far from the near year-round sunshine -- and temperatures that can be 20-25 degrees warmer -- in Santa Clara, where most players and coaches already live.
The 49ers will host Peyton Manning and the Denver Broncos in the first preseason game at Levi's Stadium on Aug. 17. The first regular-season game will be against Chicago on Sept. 14, a Sunday night.
The first event at Levi's Stadium will be a Major League Soccer game between the San Jose Earthquakes and the Seattle Sounders on Aug. 2. Other major events include the Pac-12 championship game, the upgraded San Francisco bowl game -- formerly known as the Fight Hunger Bowl -- and a regular-season college football game between California and Oregon.
York said the only promise he has not delivered on with the stadium is a Super Bowl title, and he joked with players and coaches in attendance that there's "no pressure, guys." He also said the 49ers will hold a parade on Market Street in San Francisco when -- not if -- they win another Super Bowl title.
"Now," he said, "it's time to make some new memories in our new home."
The Associated Press contributed to this report.