The Billericay born striker had been at Spurs since the age of 10 and had a few spells on loan which included Crewe.
Barnard arrived at Crewe back in August after the club had been linked with the Spurs hotshot during the whole summer.
Barnard scored on his debut in a 2-0 victory over Huddersfield Town and went on to three goals in nine games for the Railwaymen.
Injury restricted Barnard especially a crunching tackle against Luton Town in October which sidelined the player for six weeks with ankle ligament damage.
Only three weeks ago the players loan spell at Gresty Road and the player rejoined Spurs hoping to impress Juande Ramos but with 23-year-old Barnard out of contract the Shrimpers have swooped.
Southend visit Crewe towards the end of the season and no doubt the player will recieve a good reception after the player said he enjoyed his spell at Crewe.