Councillors representing the New Forest National Park Authority voted in favour of instigating the Cycle Charter.
There are 30 clauses containing guidance for people organising cycling events in the New Forest.
The cap on the number of cyclists in large events has been called "discriminatory" by CTC, the national cycling charity.
New Forest National Park Authority chairman Oliver Crosthwaite-Eyre said: "The vast majority of cycle events are under this threshold and have been operating without any complaint for many years.
"The figure of 1,000 has been well received by parish councils.
"We hope that all event organisers will follow the charter's criteria even if they don't agree with it all."
The charter will be sent to all cycle event organisers, the authority said.
The Safety Advisory Group for the forest will work with event organisers and review each event on a "case-by-case" basis.
Sam Jones, campaigns co-ordinator for CTC, said: "The cap in cycling numbers was loosely justified on safety grounds.
"It is therefore mystifying and incredibly frustrating that our amendment, which placed the Safety Advisory Group at the very heart of decision-making for each and every cycle event, was rejected.
"Instead, an arbitrary and discriminatory cap with no foundation in evidence will be implemented."
A voluntary charter restricting the number of cyclists in events to 1,000 has been approved for the New Forest.