The Spitfires fell to defeat at Roots Hall as two first-half goals gave the hosts all three points.
An emphatic first-half performance from the hosts ensured they left with a victory.
Early goals from Noor Husin and Harry Cardwell took the game away from Eastleigh as they fell to their second defeat of the season.
However, the Spitfires started the game the brighter of the two sides when in the first minute, Chris Maguire had an effort on goal blocked inside the penalty area.
Moments later Jack Bridge broke down Southend’s left-hand side, where his goal-bound strike was smartly blocked by an Eastleigh defender.
In the tenth minute, the game was brought to a halt after the Southend fans began throwing tennis balls onto the pitch in protest of their owner, Ron Martin.
In the 17th minute, the hosts took the lead through Noor Husin.
The ball found its way to Husin who calmly slotted past Joe McDonnell after a blocked effort broke to him inside the 6-yard box.
Southend continued to threaten and they nearly added to their lead when Harry Cardwell headed a looping cross inches wide just moments later.
The hosts continued their dominance and eventually doubled their lead in the 26th minute.
Bridge broke free down the left-hand side again before hitting a low cross for Cardwell to tap the ball in from close range.
In the 34th minute the Spitfires had a golden opportunity to reduce the deficit when Maguire missed the goal from three yards out after an inch-perfect cross was drilled in by Scott Quigley.
Just before the half-time interval, Southend almost made it three, when McDonnell was forced into a finger-tip save to deny Dan Mooney.
The chances continued for the hosts as captain Nathan Ralph headed inches over in the fourth minute of first-half stoppage time.
The first chance of the half came in the 61st minute when Collin Andeng Ndi was called into action for the first time this game to palm away a Maguire free-kick.
Aidan Barlow then went close two minutes later after an audacious effort from range just sneaked past the Southend goal.
Callum Powell had an effort from the edge of the box saved by McDonnell ten minutes from time which proved to be the last real chance of the game.
Report by Josh Jablonski
Southend United: Andeng Ndi (GK), Scott-Morriss, Ralph (C), Kensdale, Bridge, Husin (89), Cardwell, Mooney (73), Taylor, Miley, Fonguck (63)
Subs: Powell (73), Wood, Demetriou (89), Coker (63)
Eastleigh: McDonnell (GK), Clampin (65), Francillette, Carter, Taylor (C), Barlow, Langston, Nwabuokei (65), Maguire, Quigley, Rutherford
Subs: Scott (GK), Atangana, McCallum, Boldewijn (65), Hodson (65)
Attendance: 5696 (73 Away)
