Millwall will play Oxford United in the Football League Trophy Southern Final after they saw off Southend United at Roots Hall.
The Essex outfit started on the front foot, with John White producing a menacing cross, which Byron Webster needed to cut out.
Moments later, Ryan Leonard tried his luck from distance for Phil Brown's men, but failed to test Lions keeper Jordan Archer.
Archer was involved again later in the first half, when he produced a flying save to deny David Worrall with a well-struck effort.
Southend's inability to make the most of their pressure before half time was punished as Millwall took the lead after Steve Morison scored from close range.
Just after the hour mark, the Lions sealed their place in the Southern final when Shaun Williams fired a low drive past Daniel Bentley.
