A place on the periphery seems highly unlikely under Moyes, who first signed the South Africa international from Borussia Dortmund in 2007, also on an initial loan deal.
"If someone believes so much in you and shows so much respect for you as a player, for me I just have to go out and give 120 percent every week and hopefully this time around we can win silverware," said Pienaar, whose club last claimed a major honour by winning the 1995 FA Cup final.
"This is the fourth time (signing for Moyes). The manager knows I am an honest person who will give my all. I think that has stuck in his mind and that is why he has so much faith in me."