Three quarters of the new cases were young people in their 20s and 30s. The governor said the spike could be attributed to the young population in Japan's capital partying and dining together.
Koike said a sizeable number of new infections were workers from night entertainment businesses.
The 224 new cases represent a sudden increase in cases after the city reported only 75 cases on Wednesday, after reporting over 100 cases for six days in a row.
However, Koike added that the jump in infections could be partly attributed to increased testing in Tokyo, saying that 3,400 tests were conducted in the city on Thursday alone.