Tamworth survived Alan Neilson's sending off to hold on for victory.
Tamworth went ahead just after the half-hour mark when Taiwo Atieno's shot was deflected into his own net by Stevenage defender John Nutter.
Atieno then doubled the lead early in the second half after getting his head to John McGrath's free-kick.
George Boyd reduced the deficit for the visitors but, although Neilson was sent off for his second bookable offence, Tamworth clung on.
Tamworth: Bowles, Kemp, Weaver, Thomas, McGrath (Moore 90), Neilson, Deakin (Storer 68), Smith, McCallum, Williams (Ward 76), Atieno.
Subs Not Used: Law, Belford.
Sent Off: Neilson (72).
Booked: Neilson, Thomas.
Goals: Nutter 32 og, Atieno 52.
Stevenage: Julian, Fuller (Dobson 54), Gaia, Goodliffe, Nutter, Hicks (Henry 54), Miller, Lee, Guppy, Morison, Boyd (Stamp 84).
Subs Not Used: Potter, Oliver.
Goals: Boyd 57.
Ref: D Coote (Newark).
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