Short version: No. No league rule, no NCAA rule and no state law says you must have an agent to sign. The NFL's own agreement lets a club negotiate with "the player, if he is acting on his own behalf." The laws regulate the agent, not you.
No. The written rules at every level say you may have an agent. None says you must. Here is what each one says, with the text.
The NFL
The collective bargaining agreement sets who a club may negotiate with. A league memo in 2023 restated it: an offer sheet or player contract "may only be negotiated with the player, if he is acting on his own behalf, or with the player's NFLPA certified agent."
A club that negotiates with anyone else is fined, and the contract is void.
The players' union writes the same thing into its agent regulations. "No person (other than a player representing himself) shall be permitted to conduct individual contract negotiations on behalf of a player" without certification. The exception is written for you.
The agreement also gives an unrepresented player a direct line.
A player about to become an unrestricted free agent who has no certified agent "shall be permitted to communicate directly with front office officials" during the negotiating period. Lamar Jackson used these rules to negotiate his own contracts.
"The player, if he is acting on his own behalf." That is the NFL's phrase, not ours.
The NBA
First-round rookie contracts are paid on a fixed scale. The union's standard agent contract sets the fee at 4 percent of pay above the league minimum and 2 percent at the minimum, unless the player and agent agree to less.
Nothing in those rules makes an agent a condition of signing.
College
The NCAA's policy of July 1, 2021 says athletes may use professional service providers, including agents, for name, image and likeness work. "May" is the word.
Under the House settlement a school pays its athletes directly, and the pending federal bills protect your right to retain an agent without losing eligibility. A right to have one is not a duty to have one.
What college athletes are hearing comes from somewhere else. ESPN's survey of 1,000 college athletes this year found 18 percent had someone help with deals in high school, and two in three of those gave that person a cut.
The median cut was about 20 percent. A certified NFL agent may take 3 percent of a playing contract.
High school
State law decides. In Texas an athlete under 17 cannot sign with an agent at all. The Austin American-Statesman this week described the calls that start in sophomore year anyway: exposure, marketing, "some money up front", 5 percent for "recruiting, marketing and all these things".
What the laws regulate
The federal Sports Agent Responsibility and Trust Act, the state athlete-agent acts and every union's rules regulate the agent: who may act as one, what they must disclose, what they may charge, what they may not promise.
None of them places a requirement on you. The guide at leaveyouragent.com/be-your-own-agent walks the law at every level and lists eleven athletes who signed for themselves.
What Leave does with this
Upload the contract and Leave reads it back in plain words, with the fee, the term and who gets paid labelled. Leave takes 0 percent of anything you sign.
If someone has told you that you needed an agent before you could sign, the rule above is the one to hold it against. You decide what to sign.
Questions people ask
Can an NFL team refuse to talk to me because I have no agent?
The league's agreement says the opposite. A club may negotiate a contract with the player himself or with his NFLPA-certified agent, and with no one else. A club that negotiates with an uncertified person is fined.
Does the NCAA require an agent for a deal?
No. Since July 1, 2021 the NCAA's policy says athletes may use professional service providers such as agents. It is permission, not a requirement.
Can a high school athlete sign with an agent?
It depends on the state. In Texas an athlete under 17 cannot sign with an agent at all. Your state's rule is the one that counts.
Be your own agent. Leave.