Human rights organisations including Amnesty International, ALQST, MENA Rights, the Gulf Centre for Human Rights, and the European Centre for Democracy and Human Rights (ECDHR) all wished Hathloul a happy 30th birthday on Twitter.
Many social media users repeated Amnesty's call for Hathloul to have a "happy and resilient" birthday, her second behind bars on charges the human rights organisation has called "bogus".
Human Rights Watch's Executive Director Kenneth Roth was joined by the organisation's Middle East research Adam Coogle and others in wishing the activist a happy birthday and protesting her continued imprisonment.
US Congresswoman Suzanne Bonamici also noted Hathloul's birthday, calling the activist's treatment in prison a "clear sign of the human rights violations occurring in Saudi Arabia".
DW Freedom, PEN America and English PEN also noted the day and protested against the activist's continued imprisonment.
Advocates from across the globe came together on Wednesday to wish Hathloul - and her fellow detainees - freedom for the milestone birthday.