Published Wednesday, 11 January 2012
They will now stay in the province until at least June 2014.
Pienarr, a World Cup winner with South Africa, is into his second season at Ravenhill - he has welcomed the news.
"It's great to finally have the deal, the result," he told UTV,
"I know then I'm staying here for a bit longer. I've really enjoyed my first season here so far and it's good to extend it and looking forward to the next couple of years."
Marshall, who has been an Ulster player since 2006, admits he's been playing some of the best rugby of his career this season.
"I've just really enjoyed my rugby this season and last season and I think I've tried to eradicate a few errors," he said.
"I've tried not to do everything in ten minutes which I maybe tried to do when I was younger and I think I've just been able to read the game a bit better and I'm picking my moments when to kick, when to pass, when to make a break and I think that's certainly telling at the minute."
The news takes on extra significance because of the proposed new rules by the IRFU which will limit the number of foreign players that Ulster, Munster and Leinster can all sign from 2013.
Springbok Ruan Pienaar says he has settled well in Belfast with his wife - and there will soon be a new arrival in the family.
He continued: "She has settled in nicely, I was a bit scared of how that was going but she's settling in nicely and we are expecting our first baby on the way, in the next couple of weeks so we are expanding as a family over here so I'm really enjoying it."
Meanwhile on the pitch, the contracts come as good news as Ulster prepare to meet Leicester in the Heineken Cup on Friday.