Dobre replaces Thierry Van Cleemput, whose collaboration with Halep lasted only a matter of weeks after being confirmed in February.
Van Cleemput came in for Darren Cahill, who split from the former world number one in November, stating his intention to take a 12-month hiatus from coaching for family reasons.
Halep, Australian Open finalist and French Open champion in 2018, ended last year top of the WTA rankings.
However, she has since been displaced by Naomi Osaka, who followed up on her maiden grand slam triumph at the US Open with victory in Melbourne.
Serena Williams ended Halep's challenge at the Australian Open in the last 16, and the Romanian has now turned to Dobre as the world number three seeks to defend her Roland Garros title in May.
The 27-year-old has previously worked with Dobre in 2015. He and Cahill were each part of her team at that year's Wimbledon after she split from Victor Ionita.
"I have worked with him before so he knows me really well and I feel happy that he is in my team," Halep said.
"I trust him and we had a good collaboration in the past and I think the most important thing is that I feel good with him and we have a good connection."
Halep has a bye for the first round of this week's Miami Open. She will face either Johanna Larsson or a qualifier in the second round.