The England Under-21 international converted a 22nd-minute penalty then produced a superb solo effort 14 minutes after the break to end Boro's dismal run of four successive home defeats.
Johnson's opener was his first at the Riverside Stadium this season and the first his side had managed in 297 minutes at home after successive defeats to West Brom, Leicester and Watford.
A continuation of that run tonight might have proved fatal to Southgate with speculation mounting that chairman Steve Gibson is losing patience.
Gibson would nevertheless have been dismayed to see the banks of empty seats this evening with just 17,459 watching, the lowest ever at the stadium for a league game.
Boro started brightly and might have gone ahead with just four minutes gone when striker Leroy Lita picked out Johnson in space on the left.
The winger surged into the box and, after beating advancing goalkeeper Stephen Bywater to the ball, picked out Gary O'Neil at the far post, but his shot was deflected behind for a corner.
Derby striker Kris Commons limped off to be replaced by Paul Dickov with only 12 minutes gone, and the newcomer went close within seconds, running onto Rob Hulse's lay-off before shooting wide of Brad Jones' left post.
Lita would have been in on goal had he been able to collect full-back Joe Bennett's intelligent pass, but it was Johnson who fashioned the opening and then made the breakthrough with 22 minutes gone.
His pace as he cut inside from the left was too much for central defender Shaun Barker, who tripped him to concede a penalty, and the winger made no mistake from the spot.
Jeremie Aliadiere shot just wide after turning smartly on Sean St Ledger's 29th-minute pass and the visitors were relieved to hear the half-time whistle.
Jones had to make his first save of the game with 58 minutes gone when Dickov took aim from distance, but Johnson effectively ended the game as a contest within seconds.
Bennett picked him out on the left and he carved his way past four white shirts before curling a delightful shot beyond Bywater's despairing dive.
Gary Teale might have pulled one back for Derby within a minute had David Wheater not got in a vital block, but Johnson would have completed a hat-trick with 22 minutes remaining had Dean Leacock not blocked his goal-bound effort.
2009/10 BORO RESULTS
MACCLESFIELD 0 BORO 3 (Arca pen, Emnes, Franks)
(1st half) Coyne, Hoyte, Huth, Williams, Grounds, Yeates, Walker, Digard, Cronesberry, Aliadiere, Martin. (2nd half) Coyne, McMahon, Bates, Hines, Johnson, Smallwood, O'Neil, Arca, Porritt, Emnes, Franks.
DUMBARTON 0 BORO 5 (O'Neil, Dunlop og, Aliadiere pen, Adam Johnson, Williams)
Jones (Coyne 46), Hoyte (McMahon 72), Bates (Wheater 72), Huth (Hines 72), Grounds (Taylor 72), O'Neil (J Johnson 72), Arca (Capt) (Williams 72), Digard (Walker 29), Yeates (A Johnson 65), Aliadiere (Franks 46), Emnes (Porritt 63).
CARLISLE 0 BORO 2 (Adam Johnson, Williams)
Jones (Coyne 60),McMahon,Taylor (Williams 72),Bates(Walker 24),Huth,Wheater (Hines 60),O'Neil,Arca(Hoyte 60) 60),Franks,Yeates (Porritt 72),A Johnson (Martin 84)
OLDHAM 2 BORO 2 (Williams, Huth)
Coyne; Williams, Wheater (Huth 64), Hines, A Taylor; Hoyte (McMahon 64), Walker (Yeates 54), Arca (Smallwood 79), A Johnson (Martin78); Aliadiere(J Johnson 78) Franks (Porritt 78) Substitutes (not used): Ripley
MILLWALL 1 BORO 1 (Williams)
Coyne (Jones 46), Hoyte (McMahon, 61), Huth, Wheater, Ground, Yeates, Arca (O'Neill 46), Digard (Williams, 61), Johnson, Aliadiere, Emnes (Franks, 81) Subs not used: Adan Smith, Seb Hines , Andrew Taylor, Josh Walker, Nathan Porritt Goals: Wheater OG 27mins, Williams 78m.
BORO 0 SHEFF UTD 0
Coyne, McMahon, Wheater, Huth, Grounds, Yeates,Williams, Digard (O'Neil 42), Adam Johnson, Aliadiere,Emnes (Lita 65).
Subs Not Used: Steele, Hoyte, Taylor, Arca, Franks.
SWANSEA 0 BORO 3 (Adam Johnson, Emnes, Tuncay)
Coyne, McMahon, Wheater, Huth, Williams, Grounds, Yeates (Arca 85), O'Neil, Adam Johnson, Lita (Franks 79), Emnes (Sanli 67).
Subs Not Used: Steele, Hoyte, Taylor, Hines.
SCUNTHORPE 0 BORO 2 (Adam Johnson 2, 1 pen)
Coyne, McMahon, Williams, Huth, Grounds, Yeates (Arca 84), O'Neil, Wheater, Adam Johnson (Hoyte 90), Lita (Sanli 74), Emnes.
Subs Not Used: Taylor, Hines, Franks, Steele.
BORO 2 DONCASTER 0 (Tuncay, Lita)
Coyne, McMahon, Wheater, Huth, Grounds,Yeates (Aliadiere 72), Williams, Arca, Adam Johnson, Lita (Taylor 84), Emnes (Sanli 16).
Subs Not Used: Steele, Hoyte, Hines, Bennett.
NOTTINGHAM FOR 2 BORO 1 (Adam Johnson) Carling Cup AET
Coyne, Hoyte, Wheater, Huth, Taylor, Yeates,Williams, Arca (Bennett 106), Adam Johnson, Aliadiere (McMahon 83), Emnes (Lita 65).
Subs Not Used: Steele, Grounds, Hines, Franks.
BRISTOL CITY 2 BORO 1 (Adam Johnson pen)
Coyne, McMahon, Wheater, Grounds, Taylor, Adam Johnson, Arca, Williams, Yeates, Lita, Emnes (Aliadiere 71).
Subs Not Used: Steele, Hoyte, Walker, Hines, Bennett, Franks.
BORO 3 IPSWICH TOWN 1 (O'Neil, Aliadiere 2)
Coyne, McMahon, Wheater, Hines,Taylor (Grounds 41), O'Neil, Williams, Arca (Yeates 77), Adam Johnson, Emnes, Lita (Aliadiere 61).
Subs Not Used: Jones, Hoyte, Bennett, Franks.
SHEFF WED 1 BORO 3 (Purse og, Aliadiere, Adam Johnson)
Coyne, McMahon (St. Ledger 82), Grounds, Wheater, Hines, Williams, Adam Johnson, Arca, O'Neil (Hoyte 90), Aliadiere, Emnes (Lita 71).
Subs Not Used: Jones, Yeates, Bennett, Franks.
BORO 0 WEST BROM 5
Coyne, McMahon, Wheater, St. Ledger, Grounds,Yeates, Williams, Arca (Digard 57), Adam Johnson,Emnes (Lita 67), Aliadiere (Folan 32).
Subs Not Used: Jones, Hoyte, Hines, Bennett.
COVENTRY 2 BORO 2 (St. Ledger, Williams)
Jones, Hoyte, Wheater, St. Ledger,Bennett (Grounds 64), O'Neil, Williams, Arca,Johnson (Yeates 74), Aliadiere, Emnes (Lita 53).
Subs Not Used: Coyne, Folan, Hines, McMahon.
BORO 0 LEICESTER CITY 1
Jones, McMahon, Wheater, St. Ledger,Bennett (Digard 86), O'Neil, Williams, Arca (Yeates 62),Johnson, Aliadiere, Emnes (Lita 62).
Subs Not Used: Coyne, Grounds, Hines, Franks.
READING 0 BORO 2 (St. Ledger, Lita)
Jones, McMahon, St. Ledger, Wheater, Bennett,Yeates (Arca 70), O'Neil, Williams, Johnson, Lita (Emnes 88),Aliadiere.
Subs Not Used: Coyne, Hoyte, Digard, Grounds, Hines.
BORO 0 WATFORD 1
Jones, McMahon, St. Ledger, Wheater, Bennett (Hoyte 55), Yeates (Arca 74), O'Neil, Digard, Johnson, Lita, Aliadiere.
Subs Not Used: Coyne, Pogatetz, Emnes, Grounds, Williams.