Singer was invited to the Royals' big-league spring training camp Monday, Jeffrey Flanagan of MLB.com reports.
The 18th overall pick in the 2018 draft, Singer made his professional debut last season, posting a 2.85 ERA in 26 starts at the High-A and Double-A levels. He's unlikely to break camp with the team but could be up at some point midseason if his start to the year in Triple-A goes well.