Scrum-half Moates has torn the anterior cruciate ligament in his knee and faces six to nine months on the sidelines, while centre Jacobs has damaged ankle ligaments and will be unavailable until a few weeks after the season finishes.
Both players require surgery after suffering the setbacks on Sunday when Wasps were in Amlin Challenge Cup action against French outfit Grenoble at Adams Park.
"It's a huge shame to lose two players for the remainder of the season in one go and it's a real blow to Jack and Ben," said Wasps director of rugby Dai Young. "I know they will be working incredibly hard with our medical team to get back right."
Jacobs and Moates have played in three of Wasps' four Amlin Challenge Cup games so far this season, with the duo featuring in the record-breaking 90-17, 14-try victory at Viadana and the back-to-back wins against Grenoble over the past fortnight.
Former London Irish No9 Moates has scored three tries in this year's tournament, with the 21-year-old having crossed twice in Italy and then once in France in Rounds 1 and 3.
He scored the same number of tries in his debut Amlin Challenge Cup campaign with Irish last season, starting all six fixtures in the pool stages as the Exiles beat Mont de Marsan and Bordeaux-Begles home and away but lost their back-to-back games with pool winners Gloucester.
Jacobs, who has previously played for the Force and Waratahs in his native Australia and for Japanese outfit Kyuden Voltex, has made 17 European appearances for Wasps in his two spells with the club. He featured in all six pool games in Wasps' most recent Heineken Cup campaign in 2010/11 and in all eight matches when they reached the Amlin Challenge Cup semi-finals the previous season.