Horo, who made his NRL debut with the Eels this season after captaining Wentworthville in the NSW Cup last year, has signed for three more years, while Grothe has signed for the 2011 season.
Horo, 23, has impressed from the bench in 2010, playing 20 games and scoring three tries so far. While Grothe’s season has been hampered by a knee injury, the 30-year-old is feeling stronger than ever after undergoing surgery earlier this year.
“We’re very happy to have secured both these players for next season,” said CEO Paul Osborne.
“Justin and Eric have a strong family tradition with this club that we would all like to see continue. Eric has been a valuable member of our NRL side for many years and it’s great he’ll be back on the paddock for the Eels in 2011.
“Justin is clearly a talented player who will only improve in the future and we see him as someone who can be an important part of our forward pack for a long time.”