A double from Danny Harrison - his first for the club - saw Rotherham United record a comfortable victory to make it two league wins on the trot for the first time for a year.
It was a well deserved win as the Millers always looked the better side as they played with a different 4-3-3 formation with Ryan Taylor and Mark Hudson making their first full league appearance of the season while Pablo Mills returned after his loan spell at Crawley.
The home side were first on to the attack with Andy Warrington saving a fifth minute shot from Southam but the visitors were soon on the ascendancy with Marc Newsham winning the ball for Chris O'Grady firing wide.
A minute later they almost took an early lead when Harrison sent in a low cross and Newsham saw his shot hit the bar before O'Grady was in a good position only to slip as he was about the shoot.
A home free kick by Southam was blocked by the Rotherham defensive wall and back came the Millers again for Harrison to have a 30 yarder saved.
On 17 minutes a Steve Brogan free kick was almost turned into his own net by a Dagenham defender while at the other end the home team had a great chance to take a 22nd minute lead.
A long ball saw Ian Sharps under hit his headed back pass to leave Benson free but the striker fired wide with only Warrington to beat. Back came the Millers again for Harrison to have another 30 yarder saved while at the other end Huke fired just over the bar from 20 yards.
On the stroke of half time O'Grady had a 25 yarder saved but at the game went into added time it was United who broke the deadlock. Hudson found Newsham with a free kick and the cross picked out Harrison who glanced a header into the net with the help of a deflection from Uddin.
Early in the second half Harrison had a shot blocked while on 52 minutes he was on hand to rattle home a fine volley as he got on the end of an excellent Brogan cross.
That gave the Millers the cushion they were looking for as the home side pushed forward with Rainford shooting well wide with a free kick from just outside the penalty area.
On 73 minutes it needed a brilliant save by Roberts to keep out a goalbound Newsham header as the striker got on the end of another fine Brogan cross while the industrious Taylor went close with two good efforts.
Five minutes from time he should have got on the scoresheet when Newsham linked with Dale Tonge who sent over a fine cross that Newsham just failed to connect with but the ball fell kindly for Taylor. With the net gaping in front of him his shot into the ground went just wide when he would surely have scored with a header.
But that mattered little as the home teams efforts to reduce the arrears were restricted to corners that brought no reward with Sharps and Graham Coughlan in commanding form at the back.
Dagenham: Roberts, Huke (Taiwao 70), Southam, Graham (Green 78), Rainford, Griffiths, Benson, Uddin, Strevens (Moore 63), Foster, Smith. Subs: Thompson, Boardman.
Rotherham: Warrington, Tonge, Sharps, Coughlan, Brogan, Harrison, Mills (Hurst 85), Hudson, O'Grady (Todd 85), Newsham, Taylor. Subs: Annerson, P. Holmes, Yates.
Referee: Richard Beeby (Northants).
Attendance: 2,091 (414 away).
