The 28-year-old, who spent the second half of last season on loan at Newcastle, joins the reigning Swiss Super League champions on a season-long loan.
Doumbia made just three substitute appearances for Newcastle as they were relegated from the Premier League.
He made only six starts for Roma since moving from CSKA Moscow to the Serie A side in January 2015.
A statement on Roma's official website read: "AS Roma can confirm that it has reached an agreement with Swiss club FC Basel 1893 for the loan of forward Seydou Doumbia for the duration of the 2016-17 season."
Newcastle’s confirmed pre-season fixtures:
Bohemians vs Newcastle United - Saturday, July 16 (2pm kick-off)
Doncaster Rovers vs Newcastle United - Wednesday, July 20 (7.45pm)
KSC Lokeren vs Newcastle United - Saturday, July 23 (4.30pm)
Newcastle United vs Vitesse Arnhem - Saturday, July 30 (3pm)
AUGUST
Friday 5: Fulham (a) (7.45pm)
Saturday 13: Huddersfield Town (h) (3pm)
Wednesday 17: Reading (h) (7.45pm)
Saturday 20: Bristol City (a) (3pm)
Saturday 27: Brighton (h) (3pm)
SEPTEMBER
Saturday 10: Derby County (a) (3pm)
Tuesday 13: Queens Park Rangers (a) (7.45pm)
Saturday 17: Wolves (h) (3pm)
Saturday 24: Aston Villa (a) (3pm)
Wednesday 28: Norwich City (h) (7.45pm)
OCTOBER
Saturday 1: Rotherham United (a) (3pm)
Saturday 15: Brentford (h) (3pm)
Tuesday 18: Barnsley (a) (7.45pm)
Saturday 22: Ipswich Town (h) (3pm)
Saturday 29: Preston North End (a) (3pm)
NOVEMBER
Saturday 5: Cardiff City (h) (3pm)
Saturday 19: Leeds United (a) (3pm)
Saturday 26: Blackburn Rovers (h) (3pm)
DECEMBER
Saturday 3: Nottingham Forest (a) (3pm)
Saturday 10: Birmingham City (h) (3pm)
Tuesday 13: Wigan Athletic (a) (7.45pm)
Saturday 17: Burton Albion (a) (3pm)
Monday 26: Sheffield Wednesday (h) (3pm)
Saturday 31: Nottingham Forest (h) (3pm)
JANUARY
Monday 2: Blackburn Rovers (a) (3pm)
Saturday 14: Brentford (a) (3pm)
Saturday 21: Rotherham United (h) (3pm)
Saturday 28: Brighton (a) (3pm)
FEBRUARY
Wednesday 1: Queens Park Rangers (h) (7.45pm)
Saturday 4: Derby County (h) (3pm)
Saturday 11: Wolves (a) (3pm)
Tuesday 14: Norwich City (a) (7.45pm)
Saturday 18: Aston Villa (h) (3pm)
Saturday 25: Bristol City (h) (3pm)
MARCH
Saturday 4: Huddersfield Town (a) (3pm)
Tuesday 7: Reading (a) (8pm)
Saturday 11: Fulham (h) (3pm)
Saturday 18: Birmingham City (a) (3pm)
APRIL
Saturday 1: Wigan Athletic (h) (3pm)
Wednesday 5: Burton Albion (h) (7.45pm)
Saturday 8: Sheffield Wednesday (a) (3pm)
Saturday 15: Leeds United (h) (3pm)
Monday 17: Ipswich Town (a) (3pm)
Saturday 22: Preston North End (h) (3pm)
Saturday 29: Cardiff City (a) (3pm)
MAY
Sunday 7: Barnsley (h) (12pm)