Groff, who plays Jesse St James, appeared in the show's first season as a love interest for Rachel (Lea Michele).
However, Groff ended his relationship with Rachel by throwing eggs at her with the members of his glee club Vocal Adrenaline.
TV Line reports that Groff has now agreed to reprise his role in Glee in the final three episodes of the season.
A source claimed: "He's back to apologise to Rachel, and perhaps get her back."
Glee returns for a new episode in the US on April 19 on Fox and continues in the UK on Mondays at 9pm on E4.
> New 'Glee' episode to be extended?