Islam praises work, and there are many verses in the Qur’an that urge Muslims to work and perfect their work. The same could be found in the traditions of Prophet Muhammad (peace and blessings be upon him) where there are many hadiths that encourage Muslims to work hard.
Joining the police force or any other governmental institution is fine and there is nothing wrong with it at all as long as nobody will be oppressed. If we are sure that we will not commit injustice to people and we will abide by the Islamic rules, then the work is to be hailed. If there was any kind of injustice or humiliation to people, then this work is disapproved by Almighty Allah.

Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, illustrated: I do not see anything wrong for a Muslim to serve as a police officer. One’s mandate as a police officer is to serve and protect all citizens that make up the country; by doing so, one is not violating any of the fundamentals of Islam. As a police officer, one is not making any laws; rather one is simply helping to protect the citizens by upholding law and order.