World Cup - Waldrom joins England as cover for Easter
The uncapped Leicester number eight, who formerly played for New Zealand Under-21s and New Zealand Maori, was part of Johnson's provisional squad having qualified to play when he discovered his grandmother was born in England.
Last season, his first in England, the powerful 28-year-old was named the Premiership players' player of the season.
Waldrom, who played for the Hurricanes and the Crusaders in the Super 14, will arrive in New Zealand on Wednesday as cover for Easter, who was a late withdrawal from the England team who beat Georgia on Sunday.
"Nick Easter is still suffering from a sore back so we will be bringing Thomas out as temporary cover," Johnson said in a statement. "We've obviously spoken to Leicester and Thomas will be flying later today."
England are still to decide on a replacement for prop Andrew Sheridan, who was ruled out of the tournament last week.