The DTP was left with 19 members in the 550-seat legislature after two deputies, including Turk himself, were stripped of their seats as part of the court ruling.
The politicians had come under pressure from both Turkish and Kurdish activists to stay in parliament to demonstrate their commitment to a political solution to the Kurdish conflict.
Turk said that Abdullah Ocalan, the PKK leader, who is serving a life sentence on the prison island of Imrali, had also sent a message through his lawyers urging them to reconsider their decision to resign.
"Ocalan has said that it is not a right decision to leave parliament and that this fight should continue," he said.
The DTP leader said the 19 politicians would now join the Peace and Democracy Party (BDP), a small recently founded Kurdish group, rather than sitting as independents in the legislature.
The 25-year-old conflict between the government in Ankara and Kurdish fighters seeking autonomy from Turkey has claimed tens of thousands of lives.
The government said on Thursday that it remained committed to a plan to expand Kurdish freedoms in a bid to erode separatist sentiment among Kurds and end the fighting.