He made his professional regular season debut in the Philadelphia Eagles' season-opener at the Washington Redskins and made his first career reception on an 11-yard pass by Michael Vick in the first quarter of their 33–27 victory. He was targeted three times, but only finished with one reception. On September 29, 2013, Ertz earned his first career start after surpassing James Casey on the depth chart and was designated as the top receiving option at tight end. He finished the Eagles' 52–20 loss at the Denver Broncos with one reception for 38-yards. In Week 9, he made five receptions for 42-yards and caught his first career touchdown during a 49–20 victory at the Oakland Raiders. He scored his first career touchdown on a 15-yard pass from quarterback Nick Foles in the second quarter and caught the fourth of the NFL-record tying seven touchdown passes thrown by Foles during the game. On December 1, 2013, Ertz made five catches for a season-high 68 receiving yards and two touchdowns during a 24–21 win against the Arizona Cardinals in Week 13. It marked his first career game with multiple touchdown receptions. In Week 15, he caught a season-high six passes for 57-yard in the Eagles' 48–30 loss at the Minnesota Vikings. He finished his rookie season in 2013 with 36 receptions for 469 receiving yards and four touchdowns in 16 games and three starts.