Heyward-Bey, the seventh overall pick in April's draft, reported to training camp on Thursday and is expected to practice on Friday.
"It feels great to get it done," he said. "I wanted to be here as soon as possible. I told my team that and we got the job done."
Oakland did not reveal terms of the contract, but a person involved in the deal told ESPN on condition of anonymity that the seventh overall pick will get a base salary of $38.25 million along with the guarantee.
The seventh pick in last year's draft, Sedrick Ellis, got $19.5 million in guaranteed money from the Saints.
"I think it's big because we want him to be a big part of the offense," Pro Bowl cornerback Nnamdi Asomugha said. "Everybody was waiting on him to come in. I think that's great that he signed."
The Raiders were able to get the deal done before Heyward-Bey missed too much time in training camp. The team was dealt a serious setback in 2007 when No. 1 overall pick JaMarcus Russell missed all of training camp and did not sign a contract until after the first game of the regular season.
His rookie season was almost a complete loss and the team considered him a rookie still for most of last year.
"He needs to be here," Russell said. "I missed a whole lot. ... I hope he gets here and gets a chance to work with us."
The Raiders are counting on a big contribution from the rookie this season. They need plenty of help at wide receiver after getting just 82 catches from the position last season, led by Johnnie Lee Higgins' 22, and needed to get their star rookie in camp quickly.
"It can hurt your development as a player," Asomugha said. "When you're coming into training camp as a rookie you have to be there to see how it goes. You have to get into a groove. In 2007 that didn't happen. That's good to get it out of the way now. He only missed one practice. It's good for him."
The deal with Heyward-Bey was the highlight on a first day of practice that featured a heavy dose of fundamentals.
The team repeatedly lined up and snapped the ball, before a whistle immediately blew to stop the play as the focus was on proper footwork and alignment instead of running plays and hitting.
"Minicamp is a lot like going to Disneyland," coach Tom Cable said. "You get through it and enjoy it and you're learning all that, and to me, this is like the U.S. Open, every shot counts. Every practice, every rep. ... Every rep counts because you're learning something, you're getting back, getting your mind lined up right."
The Raiders will spend the first four days of training camp working on the mental part of the game more than the physical. There will be lots of individual drills, time spent reinstalling the schemes taught in the offseason and the aborted plays.
Next week, the players will finally put their pads on and practice. The get-back-to-basics focus is definitely different, but the players say it was needed on a team coming off its sixth straight season of at least 11 losses.
The Raiders are hoping for something different this year under Cable.
The Raiders were almost at full strength at the start of camp. Former Pro Bowl defensive end Derrick Burgess has not reported to camp as he looks to be traded. Left guard Robert Gallery is out after undergoing an emergency appendectomy and receiver Javon Walker was placed on the physically unable to perform list after offseason knee surgery.
The Associated Press contributed to this report.