The 2005–06 Nemzeti Bajnokság I, also known as NB I, was the 104th season of top-tier football in Hungary. The league was officially named Borsodi Liga for sponsoring reasons. The season started on 30 July 2005 and ended on 2 June 2006.
Debreceni VSC successfully defended their championship, and became the first hungarian club in the 21st century to win back-to-back league-titles. DVSC didn't lose a single game during the first half of the season, and went unbeaten at home for the entire campaign. One of their only two losses that season came against Újpest. UTE and DVSC were joint on points going in to the last day of the season. Debrecen defeated, and in the process relegated Lombard Pápa, while Újpest suffered their only home loss of the season against Fehérvár, who themselves finished 3rd. The club from the capital came within inches of the title, but had to watch as it slipped through their fingers again.
Ferencvárosi TC did not receive a 1st Division license due to monetary predicaments, and were relegated from the top-flight for the first time in their over century-long history.