Colchester secured promotion, while MK Dons and Hartlepool were relegated.
On a dramatic final day of the season issues at both ends of the league were resolved, but strangely all the significant positions remained completely unchanged.Southend were confirmed as champions with Colchester also going up, while Barnsley and Swansea booked their play-off places. Results also saw Hartlepool and MK Dons relegated.
Southend were already assured of promotion, but they secured the title with a 1-0 victory over Bristol City.
It was Shaun Goater's farewell appearance for The Shrimpers, but the veteran striker did not complete the match. His replacement Wayne Gray scored the all important goal three minutes from time.
Colchester headed into the final round of games in second and with a chance of topping the division, but they will just have been thrilled to secure the one point they needed to go up to The Championship automatically, after drawing 0-0 with Yeovil.
Brentford must settle for third after being held 2-2 by Bournemouth at Dean Court. Sam Sodje (22) and Andrew Frampton (65) netted for Martin Allen's side, but strikes from Steven Foley (45) and Steven Fletcher (90) sealed a point for the resilient Cherries.
At the bottom of the table the game at Millmoor between Rotherham and Milton Keynes Dons took centre stage, with Danny Wilson's side needing to win in order to have a chance of survival.
In a scrappy first half The Dons failed to show the urgency their fans would have expected, although striker Izale McLeod did pose a constant threat.
Needing only a point to maintain their League One status Rotherham comfortably held their own, apparently finding the right combination of positive forward play and staying tight at the back.
Mk Dons tried their utmost after the break but The Millers held their nerve and continued to carve out the clearer opportunities, forcing keeper Matthew Baker into action on numerous occasions.
The score remained goalless and the final whistle sparked jubilant scenes on The Terraces, while MK Dons slumped to the floor, contemplating their future in League Two.
Hartlepool were the other side in the relegation equation, but they failed to earn the three points they needed at home to Port Vale, drawing 1-1.
After a tight first half the deadlock was broken by Michael Cummins (77), and although James Brown (86) did equalise, Hartlepool were sent down along with MK Dons, Swindon and Walsall.
Play-off places were still up for grabs at three o'clock, but the sides occupying fifth and sixth, Barnsley and Swansea, both won to join Brentford and Huddersfield in the running for a promotion place.
Barnsley beat Walsall 2-1 at The Bescot Stadium. Marc Richards' first half goal (31) had been levelled by Dean Keates (59 - penalty), but Daniel Nardiello converted a spot-kick of his own to settle the result.
Leon Knight scored a hat-trick as Swansea thumped Chesterfield 4-0. Goals after five, 79 and 89 minutes, together with a Rory Fallon finish (33) emphatically protected their place in the top six.
Nottingham Forest will again be competing in League One next term after they could only draw 1-1 at Bradford. Dean Windass (20) put the home side ahead and, despite Julian Bennett's late effort, Forest finished the season in seventh
Doncaster also had a slim chance of making the play-offs and did manage to beat Tranmere 2-0, Lewis Guy (12) and Neil Roberts (43) getting on the scoresheet, but results elsewhere ended their hopes.
Huddersfield, already certain of a play-off spot, played out a goalless draw with Swindon in a stale end-of-season affair.
The day's other games had little riding on them, but allowed the teams involved the chance to end the season on a high.
Blackpool and Gillingham drew 3-3 at Bloomfield Road. After Matthew Blinkhorn (13) had fired The Seasiders ahead Darren Byfield struck twice (28 and 52) for the visitors, but there were further twists in the tail.
Blackpool had appeared to wrest the points away from Gillingham when Keigan Parker (56 and 69) grabbed a brace, before Michael Flynn (86) scored a late leveller.
Oldham and Scunthorpe drew 1-1 at Boundary Park, David Eyres (45) slotting home for Athletic and Billy Sharp (88) on target for The Iron.
Click below for match summaries
Blackpool 3-3 Gillingham
Bournemouth 2-2 Brentford
Bradford 1-1 Nottm Forest
Chesterfield 0-4 Swansea City
Hartlepool 1-1 Port Vale
Oldham 1-1 Scunthorpe
Rotherham 0-0 MK Dons
Southend 1-0 Bristol City
Swindon 0-0 Huddersfield
Tranmere 0-2 Doncaster
Walsall 1-2 Barnsley
Yeovil 0-0 Colchester
