Tauranga's 60-year-old resident rock star had earlier pleaded not guilty to a threatening to kill charge, as well as possession of 130 grams of cannabis and 0.7g of methamphetamine, but changed the plea to guilty at Tauranga District Court.
However, a conviction has not been entered.
Rudd earlier arrived at court in a late-model sports car, wearing a black suit with a red tie.
Flanked by security guards, he responded to questions with silence as a throng of media crowded his path to Courtroom 3.
Rudd was remanded on bail for sentencing on June 26.
Since the charges were laid in November, Rudd spent the summer on bail in his guarded waterfront home in Harbour Drive, Tauranga.
After police raided the home on November 6, the rocker was charged with attempting to procure murder, threatening to kill, and possession of methamphetamine and cannabis.
However, police then withdrew the attempting to procure murder charge the next day, and his then lawyer Paul Mabey QC said the damage it had brought to Rudd's reputation was "incalculable".
- By Jamie Morton of the New Zealand Herald
