He told the club website: "I've enjoyed my time here and it feels right to stay. It was an easy choice for me."
Leigertwood has made seven starts for the club and since his arrival the Royals have only conceded four goals.
He added: "The supporters have been great with me as well so long may that continue.
"I am pleased to be working with the manager, we've got a good mix of youth and experience in the squad. He has always said we want to get into the top six, we're only six points off second and it's there for us."
Reading manager Brian McDermott said: "I'm delighted, Mikele has been a really good addition to the squad. He is a top guy, a top person and represents everything that is good about this football club."
Source: BBC Sport
Source: BBC Sport