Tries from Tom Cruse and Dallan Murphy gave the RFU Championship side a slender 12-10 half-time lead that they extended further in the opening minutes of the second period.
Academy lock Harry Casson drove over as Worcester forced their way back and it was Howard who capped the performance with a late score.
Director of Rugby Dean Ryan had split his squad for the two pre-season games, with Cardiff Blues to follow on Saturday.
And this battling performance in persistent second half drizzle would have given him much to ponder as Warriors continue the countdown to the new season in less than a month.
Skipper Jonathan Thomas was straight into the action as he carried into contact at pace while a penalty for not rolling away allowed Paul Warwick to kick into touch and set up a first lineout.
A huge driving lineout saw Warriors rumble up close before the ball was spun wide and Warwick popped a pass to Howard who broke a tackle to bulldoze over. Warwick added the extras for a 7-0 lead.
Thomas was prominent for Worcester in the opening minutes while Rotherham regrouped and ran some intelligent lines with Joel Gill breaking away only to be halted by Howard and then lose the ball as he looked to offload.
Worcester looked to break from deep after a stolen lineout from Nick Seymour as the ball tore through the hands of midfield duo Jon Clarke and Ravai Fatiaki before it was lost in the tackle as Howard looked to hold on.
A superb touch finder from Warwick set up another attack for the home side while Josh Drauniniu looked to burst into life with his quick feet while he showed good he could kick too after a high effort over his head forced him to retreat.
Drauniniu was again the man to spark Worcester as he stepped and glided past three men before Thomas supported on his shoulder. A penalty gave Warwick the chance to extend the lead to 10-0.
Thomas showed his nimble footwork from deep to collect the restart and break the line, but his offload to Stephenson bounced off the wing's chest and away.
Worcester's defence was holding up well as the Titans looked for gaps around the fringes before a great sidestep from Tom Cruse saw him break away and go around the last man to score a fine individual effort. Dallan Murphy added the extras to cut the lead to three points.
Jonny Arr looked to respond for Warriors as he darted away down the right and as the hosts looked to strike from close range it was Barney Maddison who dipped his hands in the ruck and was duly yellow carded.
Rob O'Donnell was unloading some big hits and the physicality of the tackles started to show as Ed Williamson was forced off for Titans with the vastly experienced back row Alfie To'oala on.
A penalty for not releasing allowed Warwick to again go for the posts, but the new fly half saw his effort push right of the uprights.
Rotherham were working exceptionally hard in defence to stop any Worcester pressure building as half-time approached
And the visitors struck again before the break as scrum half Charlie Mulchrone broke away after a quick tap penalty and then offloaded in the tackle to Murphy who dived over for a 12-10 lead to Titans.
Worcester made one change at the break as Scotland international Euan Murray replaced O'Donnell.
Murphy knocked over a penalty to extend the visiting lead while Juan Pablo Socini almost broke away but after being tracked by Stephenson he threw the ball back to nobody.
Harry Casson secured a turnover on the floor as Worcester were forced to defend in the opening minutes of the second period and Rotherham enjoyed the lion share of territory.
Warwick was short with another penalty attempt from long range before turning down another kick at goal from a similar position to instead go for the corner.
The move paid dividends as Seymour raced up close before the forwards battered the line with Academy lock Casson driven over with support from Schofield for the lead.
But the advantage lasted just two minutes as a penalty from the restart allowed Murphy to slot another three points and put Rotherham back ahead.
A spark of inspiration came from Warwick who spotted a hole and darted through to break the Rotherham resolve before feeding Fatiaki who floated a pass to Howard to score his second of the game.
Howard sparked another move from deep as he raced back before Fatiaki fed Drauniniu on the wing and then collected the ball back inside before his inventive flip back infield failed to find Worcester hands.
Dean Ryan started to use his bench as Mike Williams, Paul Hodgson and Max Stelling entered the game and the scrum half was soon in the thick of it with a superb tackle before springing to his feet to win a penalty.
Persistent rain started to fall at Sixways as the game entered the final quarter still firmly in the balance. The game was also held up for several minutes by a head injury to Josh Brown who was stretchered off.
Worcester looked to strike a killer blow with a driving lineout and when it was dragged down after menacingly marching forward a yellow card was given to Garry Law. A scrum penalty though allowed Titans to clear.
Warwick moved to infield as Danny Gray came on and Warriors started to go through the gears in hunt of a try that would finish the game.
Hooker Ed Shervington replaced a hobbling Seymour and was the immediate beneficiary of a driving lineout as he touched down and Gray added the extras for a 29-18 lead.
Laurence Pearce became the third Rotherham player to be sin binned on the night in the final minute but there was no additional score as time ran down.
02m Howard t Warwick c 7-0
17m Warwick p 10-0
19m Cruse t Dallan Murphy c 10-7
38m Murphy t 10-12
42m Murphy p 10-15
51m Casson t Warwick c 17-15
53m Murphy p 17-18
55m Howard t 22-18
73m Shervington t Gray c 29-18
Warriors: 01 Paul Andrew (Becasseau 67), 02 Nick Seymour (Shervington 73), 03 Rob O'Donnell (Murray 40), 04 Dean Schofield, 05 Harry Casson (Williams 56), 06 James Tyas, 07 Jake Abbott (Boyce 76), 08 Jonathan Thomas, 09 Jonny Arr (Hodgson 61), 10 Paul Warwick, 11 James Stephenson (Gray 67), 12 Jon Clarke (Stelling 61), 13 Ravai Fatiaki, 14 Josh Drauniniu, 15 Ben Howard
Replacements: 16 Jeremy Becasseau, 17 Ed Shervington, 18 Euan Murray, 19 Mike Williams, 20 Andrew Boyce, 21 Paul Hodgson, 22 Danny Gray, 23 Max Stelling