Is it permissible to offer the istikharah prayer [prayer for guidance and seeking a choice] after the witr prayer?
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Answering your question, Dar Al-Ifta Al-Misriyyah, states:
Almighty Allah knows best.
Source: Dar Al-Ifta Al-Misriyyah