Commenting on the temporary deal with the New Zealander, Leinster coach Michael Cheika said: "I am delighted that David was so keen to return to Leinster to provide cover over the next few weeks. He has outstanding experience as an international class operator.
"And I know how highly he is regarded by those who played with him during his last spell with Leinster, which makes me very confident in him playing an important role for us at this important stage of the season.
"The fact that the he has already worn the blue jersey and understands our culture is a real bonus.
"With Felipe Contepomi and Isa Nacewa due to return to action over the next few weeks, it is important that we maintain our momentum and David will provide the extra cover we need in the out-half position behind Jonathan Sexton."
He also won the NPC title with the Wellington Lions in 2000.
Since moving back home from Dublin to New Zealand, he has featured for Northland in the Air New Zealand Cup (between 1995 and 1998 and since 2005) and the Hurricanes in the Super 14 where he has also played for the Auckland Blues.
He was called back into the Hurricanes squad in 2006, where his experience helped the side into their first Super 14 final. He has scored 676 points in 76 appearances.
Holwell is the holder of two Leinster records from his season with the province - the most individual points scored in a Celtic League game (26 against Llanelli) and the most individual points in a Heineken Cup game (29 against Bourgoin).