The hosts had defender Josh Passley sent off for a last-man foul on Garry Thompson before Paul Hayes tapped home the opener on the stroke of half-time.
However, Thompson himself saw red for a foul and Dagenham earned their equaliser when Luke Guttridge nodded home from close range.
Cowan-Hall restored the lead moments later and the visitors held on for the win, but were indebted to keeper Ryan Allsop for a stunning save from Justin Hoyte at the death.
Injury forced Joe Jacobson to miss the trip which led to a reshuffle in the side, with Sido Jombati switching to left-back and Michael Harriman dropping into the right-back slot. Sam Wood and Luke O’Nien came back into the midfield while Marcus Bean and Gozie Ugwu dropped to the bench, and Garry Thompson returned to partner Paul Hayes in attack.
On a freezing night in East London, Wanderers kicked off defending the away end which was missing a number of Chairboys fans due to delays on the District Line, and earned a corner inside 16 seconds which found its way to Thompson but bounced behind.
Then Paul Hayes was afforded far too much time and space down the right-hand side of the penalty area but his cross lacked the power to find Sam Wood, before the spark fizzled out of the game and errors began to creep in.
Luke O’Nien almost lit up the game with a volley which flew just over the bar from distance, before Jodi Jones’ free-kick was well saved by Ryan Allsop as the ball bounced awkwardly just in front of the on-loan keeper.
But the big talking point came just before the half-hour mark when Josh Passley was sent off for a foul on Garry Thompson, bundling the striker over just outside the box as he attempted to reach Paul Hayes’ flick-on. The referee had no hesitation in showing the red card, and the resulting free-kick flashed wide as Paul Hayes drilled it goalwards.
Daggers boss John Still responded by bringing on defender Justin Hoyte for forward Oliver Muldoon, before Garry Thompson found space in the box but was denied by the outstretched hand of keeper Mark Cousins as the striker attempted to go round him.
The Blues kept knocking at the door and were rewarded with the very last action of the half when Paul Hayes broke the deadlock, converting from close range after Michael Harriman turned Sam Wood’s deep cross back across the face of goal. Hayes – born in Dagenham – could make no mistake and put the visitors well in the driving seat for the second half.
John Still’s men changed their approach at the break and took off their liveliest creators of the first period – Jodi Jones and Ashley Hemmings – bringing on considerable height in Oliver Hawkins and Frankie Raymond.
Their gung-ho approach saw them start brightly and force the Blues into conceding two corners which caused a mini panic with the ball bouncing around the box, but the best away defensive record in the division rarely looked like being threatened.
But then came a moment to give Dagenham hope when Wanderers themselves were reduced to 10 men after Garry Thompson went in with a high tackle on Joss Labadie, going over the ball and giving the referee no hesitation in showing the red card.
The hosts scrapped well and applied more pressure, as Wycombe dug in well to protect their lead against the long-ball approach, but in the end it was a well-worked move which caught the defence out. The ball was guided towards Joss Labadie on the right side of the box and he lofted in a cross which was perfect for the unmarked Luke Guttridge to nod home and level the scores.
Dagenham had real hope of going on to clinch their first home win of the season but Wanderers regained the lead almost immediately courtesy of Paris Cowan-Hall. Sam Wood was given time and space out on the left to deliver an inch-perfect cross, and the on-loan Milwall man rose above his man to send his header into the top corner beyond the despairing dive of Cousins.
The chances kept coming. Christian Doidge crashed a header against the post from a sumptuous cross and at the other end, Gozie Ugwu showed a classy turn of pace to deceive his marker as he wriggled in from the left but saw his shot saved by the feet of Cousins.
Then Oliver Hawkins drilled wide with his left foot with a speculative effort from range, before Luke Guttridge was forced off with an injury he'd sustained earlier in the half, sending his side down to nine men.
But the Daggers almost salvaged a point in stoppage time and were only denied by a stunning fingertip save from Ryan Allsop, who flew across his goal to keep out Justin Hoyte's first-time effort from a raking cross towards the back post.
It was enough to secure all three points and back-to-back away wins for the Chairboys, who move up to sixth in the table.
Wycombe: Allsop, Harriman, Jombati, McCarthy, Pierre, Cowan-Hall, Bloomfield (McGinn 90), O’Nien, Wood (Bean 75), Hayes (Ugwu 75), Thompson.
Subs: Richardson, Stewart, Kretzschmar, Amadi-Holloway.
Dagenham: Cousins, Passley, Widdowson, Hyam, Worrall, Jones (Hawkins 45), Labadie, Guttridge, Hemmings (Raymond 45), Doidge, Muldoon (Hoyte 33).
Subs: O’Brien, Dikamona, Chambers, Cureton.
Referee: Mr Keith Stroud