No. The shahada — “I bear witness that there is no god but Allah, and I bear witness that Muhammad is His Messenger” — is valid whether done privately or publicly. What matters most is sincerity.

However, a public shahada is recommended so the Muslim community knows you have accepted Islam. This allows them to support you and fulfill communal duties (like ensuring a proper Muslim burial if something happens).

Reference: Islam emphasizes intention. Prophet Muhammad ﷺ said:

“Actions are but by intention, and every man will have only what he intended.” (Bukhari, Muslim)