The 2005–06 season of the Eerste Divisie began on August 12, 2005 and ended on April 7, 2006.
The following team was promoted to the Eredivisie at the end of the season: These teams were relegated from the Eredivisie at the start of the season: The following team was admitted to the Eerste Divisie at the start of the season: The competition is divided into six periods (Dutch: periode) of six matches each.
The winner of each period (Dutch: periodekampioen) qualifies for the playoffs at the end of the season.
If the second placed team has also won a prior period, no winner is called, and the playoff slot is decided by league standing at the end of the season.
If a team that has won a period goes on to win the league title and secure promotion to the Eredivisie, the playoff spot is awarded to the highest placed team on the final league standings that hasn't already qualified for the playoffs.