Bournemouth goalkeeper Gareth Stewart enjoyed a miserable afternoon as his side slumped to their 16th league defeat of the season to remain firmly rooted to the bottom of the table.
Southend raced into a 3-0 lead by half-time and could even afford to miss a penalty after the break.
Southend were ahead in the 18th minute when Stewart could only parry a shot from Simon Francis into the path of Mark Gower to snap up the rebound.
The Shrimpers scored their second in the 23rd minute when Francis dispossessed Danny Hollands to unleash a 25-yard shot which squirmed from the grasp of the goalkeeper.
Hollands and Sam Vokes missed easy chances for Bournemouth to reduce the arrears and were made to pay when Tommy Black made the most of another defensive error.
Bournemouth's hopes were briefly raised in the 49th minute when a low centre from Warren Cummings was turned into his own net by Southend defender Lewis Hunt.
Southend were awarded a penalty in the 51st minute when Stewart lost control attempting to clear and Russ Perrett clumsily brought down Gary Hooper.
But Gower carelessly stroked his penalty wide to give Bournemouth vital breathing space.
Southend's fourth came in the 65th minute following another defensive mix-up on the edge of the area between the onrushing Stewart and Josh Gowling.
Stewart limped off after 72 minutes with a hamstring injury to be replaced by the only other fit goalkeeper on the club's books, 17-year-old Ryan Pryce.
Pryce had little to do despite seven minutes being added on at the end of the match for injuries as Black shot wide from a good position as Southend pressed for a fifth.
Frustrated Bournemouth, authors of their own downfall with their defensive mistakes, had Max-Alain Gradel and Neil Young booked for fouls in the last two minutes.