The duo were in fourth place on the leaderboard going into their fifth and final dive - the forward 3-1/2 somersault - but produced their session-best score of 73.47 to edge ahead of experienced Canadian pair Jennifer Abel and Francois Imbeau-Dulac.
As expected, China once again took top honours thanks to a score of 331.50 from Li Zheng and Wang Han, including an impressive 81.90 for their forward 2-1/2 with a twist.
Earlier in the day, Reid had failed to make it through to the final of the women's 3m, while Goodfellow was similarly unsuccessful in progressing to the final of the men's 3m.
Mixed 3m synchro results in full:
1. Wang Han, Li Zheng (CHN) - 331.50
2. Tom Daley, Grace Reid (GBR) - 308.67
3. Jennifer Abel, Francois Imbeau-Dulac (CAN) - 302.67
4. Maicol Verzotto, Elena Bertocchi (ITA) - 296.25
5. Nikita Shleikher, Nadezhda Bazhina (RUS) - 294.90
6. Lou Massenberg, Tina Punzel (GER) - 294.18
7. Sebastian Villa, Diana Pineda (COL) - 266.19