The Giro d'Italia, Tour de France and Vuelta a Espana will all issue an extra wildcard team invitation in 2025, with the initiative due to be rubber-stamped on Monday.
The total number of riders will shift from 176 under the 22-team model to 184.
All 18 top-tier World Tour teams take part in the Grand Tours, with extra invites given to teams from the second-tier Pro Tour.
The Professional Cycling Council announced it had approved a motion on the matter on Monday.
"All the families represented within the CCP –- the organisers, the teams, and the riders – had jointly submitted the request that the number of teams participating in the men's Grand Tours be increased to 23 starting this year," the UCI said in a statement.
"This request was studied by the CCP today, and the proposal was accepted by the majority of its members."