Lee Novak was Spireites’ star in a fine home performance that earned them a first home win since the opening day of the season.
Novak opened the scoring before two Sylvan Ebanks-Blake poachers’ goals, one in each half, wrapped up the result.
The three points take Chesterfield to 20 for the season, one more than at the same stage of last season when they went on to make the play-offs.
Dean Saunders unsurprisingly selected the same starting eleven that won at Walsall at the weekend meaning it was 4-4-2 again and that decision was vindicated as Spireites took an early lead.
Dan Gardner picked a perfect pass to put Novak free and the striker stepped round Dan Bentley to slide the ball in low from the right side of the six yard box.
That goal gave Chesterfield visible confidence and they went on to take complete control of the first half.
The hosts won a run of four straight corners and saw long range efforts from Sam Morsy and Jay O’Shea whizz just wide.
Novak and Gardner were both at the top of their games and it was no surprise when that pair were involved in the build-up for the second, both seeing shots blocked before Ebanks-Blake pounced on a rebound to fire home from close in.
Phil Brown’s in-form Shrimpers, wearing a natty workman fluorescent yellow, came to the Proact having won six in seven, but they were limited to scraps before the break.
Joe Pigott hit wide as did Anthony Wordsworth but anything on target was under hit and easy for Tommy Lee.
Southend came out after the break much more fired up and Pigott saw Lee save at his feet and another effort roll just wide.
However the key next goal went to the Blues. O’Shea had a box-edge effort deflected over for a corner, Jones delivered, Ian Evatt rose high to head downwards, his effort was blocked on the line and once again Ebanks-Blake reacted quickest to stab home from a couple of yards to register his first brace for 30 months.
Novak came closest to adding a fourth as Spireites successfully saw out the game to register a clean sheet for the first time in ten games.
Chesterfield play host to Scunthorpe United at the Proact on Saturday, looking to make it a hat-trick of victories but they’ll be without Evatt who picked up a fifth yellow.
CHESTERFIELD: Lee, Talbot, Evatt, Raglan, Jones, Gardner (Simons 75), Herd (O’Neil 69), Morsy, O’Shea, Novak, Ebanks-Blake (Dieseruvwe 71).
Subs unused: Chapman, O’Neil, Banks, Ariyibi.
Southend: Bentley, White, Bolger, Prosser, Coker, Timlin, Leonard, Wordsworth (Payne 63), Weston, Mooney (Hurst 71), Pigott (Williams 79).
Subs unused: Smith, Atkinson, McLaughlin, Rea.