A dull first-half saw very few chances created and it was not until just after the hour mark that Byron Harrison got his 19th goal of the season to put Barrow into the lead.
The visitors doubled their lead just five minutes later as Akil Wright broke free and fired past Sam Beasant.
Barrow's Paul Turnbull was sent off late on but it had little impact on a comfortable win.
Despite the win, Barrow narrowly miss out on a play-off spot as Aldershot were 3-0 winners at North Ferriby.
The loss for Braintree sees them sit just two points above Guiseley, who are just outside of the relegation zone.
Match report supplied by the Press Association.
Match ends, Braintree Town 0, Barrow 2.
Second Half ends, Braintree Town 0, Barrow 2.
Substitution, Barrow. Elliot Newby replaces Jordan Williams.
Paul Turnbull (Barrow) is shown the red card.
Goal!  Braintree Town 0, Barrow 2. Akil Wright (Barrow).
Substitution, Braintree Town. Lee Barnard replaces Reece Hall-Johnson.
Substitution, Barrow. Ross Hannah replaces Matthew Platt.
Goal!  Braintree Town 0, Barrow 1. Byron Harrison (Barrow).
Substitution, Braintree Town. Craig Braham-Barrett replaces Kristopher Twardek.
Substitution, Barrow. Byron Harrison replaces Richard Bennett.
Moussa Diarra (Barrow) is shown the yellow card.
Second Half begins Braintree Town 0, Barrow 0.
First Half ends, Braintree Town 0, Barrow 0.
Jack Midson (Braintree Town) is shown the yellow card.
First Half begins.
Lineups are announced and players are warming up.
Braintree will go into the final day of the National League season in the relegation zone after they were beaten 2-0 at home by Barrow.