The 23-year-old Zambian star is expected to touch down in England in the coming days, to undergo a medical at the Madejski Stadium ahead of a move to the Premier League.
Gunners boss Arsene Wenger is believed to be an admirer of Sunzu, and had considered a bid to bring him to the Emirates Stadium, as he looks to further strengthen his back line.
However, Arsenal now look to have lost out on the exciting African youngster - who is under contract at Mazembe until 2015 - after the Royals stepped in to snatch his signature.
With only the formalities of the transfer to be completed, Moses Katumbi, president of the DR Congo side, confirmed:
"Indeed, Sunzu is heading to Reading for tests after the agreement by TP Mazembe and the Zambia Federation. He just sent us a message in which he thanked the club."
Sunzu has been capped 32 times for the Zambian national team, and shot to fame when he converted the winning penalty in the famous 8-7 shootout victory against pre-tournament favourites Ivory Coast at the 2012 Africa Cup of Nations.