Kyle Orton threw for 307 yards and two TD passes, including one to Eddie Royal — his first TD catch since 2008 as the Broncos dominated the Seahawks (1-1) from the start and played keep-away in the second half.
The Broncos (1-1) won their 11th straight home opener and improved to 24-3 in home openers since 1984, the best mark in major professional sports during that span.
Thomas, who missed all of the preseason and last week's opener after aggravating his surgically-repaired left foot during a scrimmage last month, hauled in Orton's 21-yard touchdown pass to make it 31-7 and cap his smashing debut.
Thomas was the first receiver selected in the NFL draft in April. Despite playing in Paul Johnson's triple-option offense at Georgia Tech, a system that's considered ill-suited for the NFL, Thomas was selected two spots ahead of the more polished Dez Bryant, who went to Dallas at No. 24.
In the former Yellow Jackets' deep threat who packs 230 pounds on his 6-foot-3 frame, Denver coach Josh McDaniels trusts he's found Marshall's lookalike but not act-alike.
Despite three straight 100-catch seasons, Marshall's antics on and off the field made him a chronic headache for the organization before his trade to Miami last spring. His four seasons in Denver were filled with drama and distraction along with run-ins with the front office and law enforcement.
Thomas has said he felt he was drafted ahead of Bryant because he's a good guy.
He's also a pretty good receiver, as the Seahawks saw firsthand.
The Broncos led 17-0 after a dominating first half that included a trio of takeaways and the debut of Thomas, who caught four passes for 56 yards in a long drive that ended with Matt Prater's 20-yard field goal just before halftime.
Hasselbeck finished 20 for 35 for 233 yards and was picked off three times, the last time by rookie Perrish Cox in waning minutes. He threw for a touchdown and ran for another.
Orton was 25 of 35 with two TDs and no interceptions.
After Vaughn's recovery of Walter Thurmond's fumbled punt at the Seattle 13, Royal caught a low pass from Orton and rolled into the end zone for his first TD catch since Nov. 30, 2008, against the Jets, a span of 22 games.
Royal set up Denver's second touchdown on a 34-yard reception to the Seahawks 1 when running back Knowshon Moreno took the pitch and then tossed back to Orton, who found Royal racing down the left sideline. Royal was tripped up by Lawyer Milloy at the 1, and Correll Buckhalter took it in from there for a 14-0 lead.
Thomas made his NFL debut on the Broncos' fourth possession and had receptions of 20, 18, 9 and 9 yards on the drive that stalled at the Seahawks 2.
The Broncos' shoddy special teams coverage — which led to 17 points in their season-opening loss at Jacksonville — showed up again in the third quarter when they had Seattle rookie Golden Tate bottled up before letting him slip free for a 63-yard punt return — he would add a 52-yard catch later on.
Tate's big return set up Hasselbeck's 11-yard TD pass to Ben Obomanu.
Moreno had a career-long 45-yard reception on the ensuing possession, which he capped with a 1-yard dive to make it 24-7.