"I've got that old-fashioned view, that if you come to America, you should commit to the idea of America: One nation, under God, indivisible, with liberty and justice for all," he says in the ad.
It features shots of him in his military uniform and meeting voters throughout Massachusetts.
The ad will run statewide, but the campaign declined to share information about the size of the advertising buy.
But it reflects the fact that many voters are just beginning to tune into the Senate race, and Gomez is still largely unknown. A new poll out Thursday revealed a quarter of voters still don't have an opinion on him — but it also indicated that those voters getting to know Gomez are impressed with what they've found.
The number of voters who view him negatively has risen since the last poll from Democratic firm Public Policy Polling, up to 34 percent viewing him unfavorably, from 27 percent in early May.
Gomez has been under Democratic attack over the past week for a controversial tax deduction he took on his home in Massachusetts, which Democrats believe shows he's out of touch with average Americans.
He's managed to keep Democrat Edward Markey's lead to single digits in nearly every poll of the race, however, and the National Republican Senatorial Committee indicated its planning on investing in his race.
The committee's involvement will likely pave the way for other GOP outside groups to get in the race, giving Gomez more freedom to introduce himself to voters, as they take on attacking Markey.
This first ad of the general election allows him to reassert his own narrative — that he's a Spanish-speaking, military veteran "new kind of Republican," as his campaign has called him.
Meanwhile, Markey's campaign went up with its first contrast ad of the general election on Thursday night, invoking the Newtown, Conn., school shootings to highlight Gomez's position on gun control.
The ad shows Markey meeting with law enforcement officers while a narrator pledges that he'll continue to "fight for common-sense laws to stop gun violence."
It then notes Gomez's opposition to a ban on assault weapons and high-capacity magazines "like the ones used in the Newtown school shooting."
"The more you know, the clearer the choice," the narrator adds at the end.
The campaign declined to offer any additional information on the buy.
Markey's campaign has already released one ad in the general election campaign, a positive spot touting his work on telecommunications policy.
The candidate's choice to launch a contrast ad reflects those persistently tight polls. But those polls indicate Markey has an opportunity to define him on the issues.
Gomez aide Lenny Alcivar said the ad, and Markey's choice to go negative, showed the Democrat is "desperate" and concerned about potentially coming up short in the election.
"Congressman Ed Markey is desperate and worried about losing this election to outsider Gabriel Gomez. In the middle of the worst Washington scandals in a generation, lifelong politician Ed Markey just launched a desperate, negative attack ad slinging mud. This negative attack proves Gabriel's message for Massachusetts is working its time for Congressman Markey to get a real job in the real world," he said.
And on Friday, Gomez came out with a statement of his own slamming Markey for invoking Newtown and reasserting his support for the Manchin-Toomey background checks bill.
“I guess after 37 years in Congress you lose your sense of decency. Exploiting a tragedy for political gain is sick," Gomez said.
--This report was originally published at 6:29 p.m. and last updated at 10:52 a.m.