The 66-year-old teacher, an Irishman who taught English, was stabbed repeatedly in front of the private Leonard-de-Vinci university in Courbevoie, northwest of Paris.
A Pakistani man was arrested Wednesday on suspicion of murder.
Sources said the suspect, who is in custody, was a former student at the university who was born in Pakistan in 1981 and was not previously known to police.It was not yet known whether Mr Dowling had taught the student.
Students and staff at the private university paid tribute to Mr Dowling, who was originally from Dublin.
Anne Bertrand a former student told The Local: “John was always in a good mood, always smiling, always joking. He was en excellent teacher, adapting to each student at their level, and giving them exactly what they needed
“His classes were the opposite of boring. Actually we had so much fun that sometimes, people working on the same floor had to ask us to keep it down!
“Mr Dowling was one of the best teachers I had throughout my whole education.”
Fellow staff member Linda McLaren said: “My heart goes out to John Dowling, fellow teacher who was brutally taken today by one of our former students.
“We had just spoken to him before leaving the university. Words cannot describe our grief as we have known John for over 15 years and he was a nice gentle man who was looking forward to his retirement.”
Stephen Amoah, a 28-year-old student from Ghana said: “It's heartbreaking. We still can't believe it.”
His classmate Jad Sharif, a 33-year-old from Lebanon, described the murdered teacher as “very kind”.
Students showed photographs of the white-bearded Irishman on their mobile phones, smiling and arm in arm with members of his class.
A statement from the Leonard de Vinci school where Mr Dowling taught paid a warm tribute to the tragic teacher.
The statement said: “On Wednesday, one of our lecturers was stabbed to death in front of the Leonard de Vinci campus. It happened outside the institution on Mona Lisa square.
“The victim is John Dowling, 66, who has been teaching English at Leonard de Vinci schools since 1999.
“The aggressor has been arrested. This person had spent a few months as a student in one of De Vinci schools and had been expelled in August 2017 as he did not validate his studies.
“John was a very friendly man, respected and loved by all students and colleagues. He was also known for his great availability and kindness.
“The community of the Pole Leonard de Vinci is deeply shocked and saddened by this tragedy of extreme violence. We express our most sincere condolences to the family and friends of John Dowling.”