He said subject to final approval, building consent and tendering, it was hoped phased construction work would begin late next year.
It was too early to comment about whether parts of the court would need to be closed during construction.
In January, after a stint working in the local High Court, a visiting Auckland lawyer wrote to Courts Minister Andrew Little calling for urgent action in Rotorua.
Barrister Sam Wimsett cited several concerns in his letter, including the fact the law library was closed as a result of mould caused by a leaking roof.
Wimsett told Little the conditions were a disgrace.
Among the worst aspects were the cells, which he said could only be accessed by walking around the street to the back entrance of the court and there was usually a line of lawyers waiting to see clients.
His calls were backed by Rotorua Crown solicitor Amanda Gordon, who described the court's cells as "feral" and said the conditions inside the building were so bad, they risked witnesses being put off coming to court to give evidence.
Gordon said this week she was pleased something was being done, although her preference was to move the courthouse away from the central city.
She said when there were gang trials in particular, it wasn't a good look to have people hanging around in groups in full view of tourists in what was effectively Rotorua's main street.
Gordon said considering the amount of work needed to fix the buildings, it might have been better to move it elsewhere. The ministry has told the Rotorua Daily Post relocating the courthouse was never an option.
Gordon said ideally she would like to see another courtroom added, new cells, a revamped entrance making security screening quicker and some of the normal features other courts had, including Wi-Fi and good air-conditioning.
She said courtroom temperatures were an issue and she told every witness she dealt with it could be either "sweltering hot" or "freezing cold".
Defence lawyer Tim Braithwaite said he had been involved in discussions about the revamp with ministry officials.
"Work on the courthouse is much needed and has been needed since before I began working in Rotorua in 2009. It is positive that we now have some progress."
He said the building was not fit for purpose and a lack of courtrooms was the biggest issue.
This meant a shortage of available court time, which contributed to delayed justice and people being denied early opportunities for bail applications and sentencing, he said.
"Often people who would otherwise be out of custody will be held in custody for weeks waiting for court time."
The layout also poses a significant risk of defendants and their counsel crossing paths with complainants and jury members, he said.
"There are many other issues, such as the horrid court cells that have received publicity previously, and the leaks that are common throughout the building.
"Tearing down the building and starting fresh would be ideal but investing in significant renovations, as proposed, is the next best thing.
"Overall it is positive to see investment in our justice system here in Rotorua that has been desperately lacking over the past decade."
