McDaniels was born Sep. 29, 2000. His brother, Jalen, was selected by the Charlotte Hornets in the 2019 NBA Draft. Jaden is also the cousin of former NBA player Juwan Howard. His father, Will McDaniels, and mother, Angela Jackson, are originally from the Windy City, Chicago. Jaden played high school basketball for Federal Way High School in Federal Way, Washington. He was teammates with his older brother Jalen and helped the school win its second straight Class 4A state title during his freshman campaign. McDaniels' stock began to rise from his junior campaign onward, and as a senior, he averaged 23.3 points, 10.0 rebounds, four assists and two blocks per game. He finished high school as the 2019 Class 4A Player of the Year and Washington Gatorade Player of the Year. He also played in the McDonald's All-American Game and the Jordan Brand Classic. For college, McDaniels attended Washington and averaged 13.0 points, 5.8 rebounds and 1.4 blocks as a freshman. After that season, he declared for the 2020 NBA Draft. McDaniels entered his first and only season with Washington with a strong recruiting pedigree, and he lived up to the hype across 31 games (21 starts) for the Huskies. As a starter early in the season, he scored a career-high 22 points Dec. 22 against Ball State. That was one of four total 20-point efforts on the year. Serving as the primary power forward alongside Isaiah Stewart in the post, McDaniels finished the year with averages of 13.0 points and 5.8 rebounds. He also showcased his skills on the defensive end, finishing with the fourth-most blocks in the Pac-12 (43). Furthermore, the 6-9 forward was plenty capable from distance, making 43 three-pointers at a success rate of 33.9 percent. McDaniels declared for the draft after the season and later signed with an agent in April, cementing his intentions of going pro.