The 28-year-old has made 214 appearances in British football after earlier spells with Dundee and Rangers in the Scottish Premier League.
"We are very pleased to add Zurab to our squad and this is another signing that will add very good experience," director of football Nick Hammond told Reading's official website.
"He can play centre-half, full-back or as a holding midfielder so he also brings excellent versatility and I'm sure he will prove to be a good addition."
Khizanishvili trained with new his team-mates on Monday and is available for Tuesday's trip to Sheffield United.
The Royals will be looking to boost their survival hopes as they currently sit third bottom in the Championship table, four points adrift of safety.
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Source: Team Talk