The 18-year-old -- who was playing in her first ever grand slam -- lost the first set and was trailing 0-3 in the second against Ajla Tomljanovic when she called on a trainer.
During the second set, she frequently bent over with her hand to her stomach, showing signs of discomfort.
A first trainer was followed by a second shortly after, with one appearing to listen to her breathing as she sat on Court One.
Having left the court for further treatment, it was announced minutes later that Raducanu would not be returning. Wimbledon later confirmed she had withdrawn from her match after suffering "breathing difficulties."
After progressing to her first career grand slam quarterfinal where she'll face compatriot Ashleigh Barty, Tomljanovic admitted she felt "sorry" for Raducanu.
"I'm actually really shocked," 28-year-old Tomljanovic said. "It's obviously bitter-sweet.
"Emma must be really hurt if she came to the decision to retire. To play as a Brit at home is unbelievable, so I'm really sorry for her. I wish we could have finished it. It's sport, it happens. I'm really wishing her all the best."
The end of the road
It was a disappointing end to a remarkable breakthrough competition for the young British player, who was ranked No. 338 before the start of the tournament.
Raducanu beat two top-50 opponents, Marketa Vondrousova and Sorana Cirstea, on her way to the last 16 and became a true fan favorite not just with her tennis abilities, but also with her acts of humility after she was seen cleaning up her own trash after her second round victory.
Raducanu and Tomljanovic were forced to wait until late into the evening to begin their fourth-round meeting due to a five-set thriller between Alex Zverev and Felix Auger-Aliassime before them.
The 75% capacity crowd was clearly in Raducanu's corner, cheering every point she won like a match winner.
However, after failing to convert some early break points, world No. 75 Tomljanovic showed her experience, claiming the first set under the Court One roof.
She was firmly in control of the second set when Raducanu retired, and the possibility of facing her fellow Australian in the next round has got Tomljanovic excited.
"Because of the circumstances, it hasn't sunk in that I'm in the quarters," she said. "But to be playing Ash, two Aussies, with one of us sure to go to the semis -- it's great. I think everyone back home is really happy. I'm thrilled to play Ash. It will be a great match."
Eight-time Wimbledon champion Roger Federer progressed to the quarterfinals of the grand slam on Monday for the 18th time, extending his own record at the competition.
The Swiss looked relatively comfortable on his way to beating 23rd seed Lorenzo Sonego 7-5 6-4 6-2 on Centre Court in the fourth round, extending his lead at the top of the all-time list for most Wimbledon quarterfinal appearances, ahead of Jimmy Connors.
"I'm extremely happy," Federer said. "Again, tricky conditions -- inside and outside -- against Lorenzo who is always dangerous, but I felt that after that first set, I was able to control things. It was a great match and I couldn't be more excited to be in the quarterfinals. It's a big moment and I'm very, very happy."
Federer will face either second seed Daniil Medvedev or 14th seed Hubert Hurkacz in the next round.