Here is a statement from Ayo Davis, Disney Branded Television President, about the renewal of the series:
“Rich in magic, wonder, adventure and heart, Percy Jackson and the Olympians captivated the imaginations of viewers of all ages everywhere. We’re thrilled to embark on an exciting new quest and a season two with Rick Riordan, our fantastic partners at 20th Television, and the exceptional ensemble of cast and creative talent that bring this story to life.”
The series made its debut in late December to positive reviews and gained 13.3 million global "views" within six days of its premiere. This number had doubled after three weeks, showcasing the popularity of the show. The series now stands as the most successful launch for a Disney+ series unrelated to Marvel or "Star Wars" to date.
Source: DarkHorizon