The hosts were in complete control throughout, and strikes from Paddy Madden, Kevin van Veen, Josh Morris, and Richie Smallwood only went to emphasise the dominance Scunthorpe enjoyed.
There were two changes to the Iron line-up, which started the last league fixture against Port Vale. Scott Wiseman replaced the suspended Jordan Clarke at full-back, while Madden came in for Tom Hopper up front.
The visitors pressed early on, and forced an opening inside of three minutes, through captain Adam Barrett. The centre-back wasn’t picked up in the area, leaving him to power a header goalwards, but Luke Daniels was up to it - reaching out a right arm to repel the effort.
Graham Alexander’s men soon came back into it though, with Josh Morris driving a shot across the face of goal, after a sustained spell of pressure beforehand.
Some fine individual play from Duane Holmes then opened up the Shrimpers’ back four. The American’s jinking run bought him a yard of space, and gave him the opportunity to test Ted Smith in the Southend goal, who saved well at the near post.
United were applying pressure, but continued to be frustrated, up until ten minutes before the interval. There were no prizes for guessing who the scorer was either, with Madden, in his first league start of the season, slotting home from close range in the penalty area.
One soon became two, as van Veen took his tally to six for the season. Following a short corner being played to Morris, the Dutchman stole in, unattended at the near post, to glance his header home, and give the Iron breathing space going into the break.
Scunthorpe began the second half as they ended the first. Madden firstly headed over at the far post, before van Veen drove a shot over the crossbar minutes later.
The home side wouldn’t have to wait too long for a third, and it was the League One player of the month Morris who got it - in some style. Reminiscent of his opening day strike against Bristol Rovers, the midfielder picked the ball up from deep, driving at the defence, before unleashing a superb left-footed strike across Smith and into the far corner to all but seal the victory.
Phil Brown’s side looked unable to cope with Scunthorpe every time they trundled forward. They were cut open again on 69 minutes, with Holmes bringing the ball forward, ahead of stinging the palms of Smith with a dipping shot from the edge of the area.
Madden thought he’d doubled his tally for the afternoon in the minutes after Holmes’ attempt, when he slid the ball under Smith and into the back of the net. His and the crowd’s celebrations were cut short however, as the linesman on the far side raised his flag to signal offside.
United were relentless, and poured forward with wave after wave of attacks. A fourth could and maybe should have been added with 15 minutes to play but, despite the best efforts of Holmes, Madden and Stephen Dawson, the Iron just couldn’t find a way through at that stage.
Holmes' endeavour and perseverance almost brought him one with 13 minutes left on the clock. The Southend backline failed to stop another fine solo run, and all that was missing was the finish, as the midfielder curled the ball inches wide of the far post.
The miss did little to detract from Holmes’ overall display though, and he was given a rapturous applause when he was substituted minutes later.
There was still time for the Iron to add a little more shine to the performance too, with debutant Smallwood getting in on the act with a fabulous strike. The midfielder lurked on the edge of the box, and watched the ball drop out of the sky, before he volleyed brilliantly into the roof of the net.
Van Veen had an opportunity to add a fifth in the dying embers of proceedings, but it didn’t take anything away from United, who were superb all afternoon.
Scunthorpe United: Daniels, Wiseman, Wallace, Mirfin, Dawson, Madden (Smallwood 77), van Veen, Morris (Toffolo 88), Bishop, Holmes (Mantom 81), Townsend.
Substitutes: Anyon, Adelakun, Goode, Wootton.
Southend United: Smith, White, Thompson, Barrett, Mooney, Cox, Atkinson, Sokolik (Coker 46), King (McLaughlin 46), Leonard, Kyprianou (McGlashan 46).
Substitutes: Oxley, O'Neill, Bridge, Demetriou.