His call-up comes in the same week that he was named Ireland's Young Player of the Year. World governing body FIFA ratified Londoner Rice's switch last week as he had not played a competitive game for Ireland.
"His form warrants it," Southgate told a news conference. "The situation has been well publicised and we have tracked him for a quite a while. "When you are asking a player to transfer allegiance they have to feel they have a future, but also there are no guarantees. But his form has been excellent.
"His character and leadership qualities means he fits in very well into the way that we work." Burnley keeper Tom Heaton has also returned to the squad for the first time since before last year's World Cup finals.
Tottenham Hotspur duo Dele Alli and Eric Dier were also included having just returned from injury and illness. England face the Czechs at Wembley next Friday before travelling to Podgorica to face Montenegro three days later. (Reporting by Martyn Herman Editing by Christian Radnedge)