Luisma Villa’s 80th minute strike saw Barnet make it two wins from two under Uli Landvreugd and Dick Schreuder.
The Bees dominated from start to finish but they had to overcome a rigid Tamworth defence and incredibly tough conditions at The Hive.
The Lambs had a penalty saved by Nick Jupp in the first-half and it looked like ending level but Villa converted with time running out before Kieron Cadogan and Jake Hyde had goals chalked off for offside.
Barnet started brightly in difficult conditions and with just two minutes played they went close when Keanu Marsh-Brown was just unable to control the ball after bursting through.
Six minutes later the Bees were on the front foot once more when Mauro Vlhete darted down the left and saw his shot blocked.
With 16 minutes on the clock Hyde saw his first opportunity of the match turn to dust as he pulled a shot wide from just outside the box after good work from KMB and Andy Yiadom.
Despite a promising start on 17 minutes disaster struck when Yiadom bundled over Justin Richards in the box and the referee pointed to the penalty spot.
Yiadom was awarded a yellow card for the challenge before Richards stepped up to face Nick Jupp but his penalty was poor and the goalkeeper went the right way ensure it remained goalless.
Hyde had a flurry of chances soon after but he smashed the first just wide from a tight angle before clipping the ball just over from a KMB cross.
Tamworth rarely ventured forward and on the odd occasion they attempted to Jack Saville and David Stephens combined to clear the danger with ease.
Chances continued to come for the Bees but the incredible wind made them almost impossible to finish with Hyde again failing to latch on to a through ball that sped towards a grateful Belford.
The second period continued in the same vein with Marsh-Brown terrorising full-back Wayne Thomas once more before being denied at the near post by Belford.
KMB continued to torment Thomas and the defender had his teammates to thank for clearing the danger after Marsh-Brown beat him again and again.
With 60 minutes on the clock on loan Brentford attacking midfielder Charlie Adams replaced Dani Lopez to make his Barnet debut.
Six minutes later Barnet were inches away from opening the scoring as Hyde swivelled in the box and shot just wide.
Tamworth responded with a chance of their own but Jupp was alert at his near post to palm Richards’ powerful effort to safety.
With 11 minutes remaining the Bees had a big penalty shout when Yiadom went down in the box but the referee waved play on.
One minute later the Bees finally took the lead when Luisma Villa slotted the ball past Belford at the second attempt.
Substitute Kieron Cadogan had the ball in the net with five minutes remaining but his effort was ruled off for offside and Hyde also had a strike ruled out but in the end it didn’t matter as three points were secured.
Barnet FC: Jupp; Yiadom, Saville, Stephens, Vilhete; Byrne, Weston, Villa (Cadogan 82); Marsh-Brown (Johnson 90), Lopez (Adams 60), Hyde.
Subs not used: Abdulla, Mengerink.
Tamworth: Belford, Evans, Palmer (Todd 75), Townsend, Baker, Richards, Thomas, Fenton, Chadwick (Peniket 77), Mahon, Morgan.
Subs: Reindorf, Richards-Everton, Keane.