A Mark Gower brace proved to be enough to help the Shrimpers sink relegated Cheltenham Town 2-0 at Roots Hall.
The new-look Southend side deserved their victory as they dominated the visitors for long periods.
The Robins looked lightweight up front and rarely looked like scoring.
Gower almost broke the deadlock in the eighth minute when he latched on to a poor backpass but Steve Book was alert enough to deny him.
At the other end Grant McCann blasted a shot wide but it was Southend who deservedly took the lead in the 33rd minute.
Gower fired a great shot past the despairing drive of Book and the hosts rarely looked like wasting their hard-won advantage.
Drewe Broughton had an effort disallowed while Mark Warren’s powerful shot was deflected wide.
Cheltenham hit back after the interval and Paul Brayson went close with a rasping 25-yard drive while Kayode Odejayi was denied by a great Carl Emberson save.
However, Southend continued to create some good chances of their own and they deserved a second goal.
It finally came in stoppage time when Gower scored his second goal of the afternoon from the penalty spot after Jim Corbett had been tripped.