Long then volleyed in from close range before half-time following a corner.
Stephane Sessegnon and Graeme Dorrans went close for the Baggies in the first half, while David Meyler failed to find the target with a header from five yards.
Steve Bruce’s side had the better chances after the break with Jelavic’s volley finding the side netting and Long rattling the post with a curling effort.
Substitute Saido Berahino had a half chance late-on for the Baggies, who have won just two of their last 20 league games.
The defeat sees them remain three points off the drop zone while the Tigers climb to 12th place.
2' SESSEGNON CHANCE - Sessegnon fires a long-range effort narrowly over.
8’ PENALTY CLAIM - Meyler was tripped in the box by Reid but it’s no penalty. Meyler did not make a meal of the challenge.
15’ DAVIES SHOT - The defender fires in a good effort towards goal which is blocked by Mulumbu.
17’ DORRENS CHANCE - Great inter -play from Thievy and Dorrens' half-volley is parried away by McGregor.
26’ – MEYLER HEADER - Meyler misses an absolute sitter! A free header from six yards out which he places wide.
29' GOAL: Hull 1-0 West Brom – Long goes down under the softest of challenges. Jelavic’s penalty is parried by Foster but Rosenior heads in the rebound.
36’ HUDDLESTONE CHANCE - Huddlestone's long-range effort is tipped over the bar, good save by Foster. That shot had some spin on it.
38’ GOAL: Hull 2-0 West Brom – Long makes it 2-0 with a simple volley from close range after the Baggies fail to clear a corner.
51’ JELAVIC CHANCE - Aluko's cutback finds Jelavic whose volley hits the side netting from six yards out.
52’ – GOOD SAVE - Following a corner, Anichebe’s header is palmed away by McGregor.
66’ – WOODWORK - Long hits the post with a curling effort from the edge of the box, Foster did not move.
84’ – CHANCE - Berahino’s side-footed effort from close range is straight at McGregor.
88’ – PENALTY CLAIM - Sagbo should have won a penalty after Ridgewell's foul but gets nothing. Chris Foy has had another controversial afternoon.
Hull are unbeaten in 20 league matches when they have led at half-time.
Liam Rosenior scored his first goal for Hull and his first of his Premier League career.
West Brom have become the eighth team to concede 4,700 top flight goals. They conceded their first goal in a 2-1 win at Derby County in September 1888.
The Baggies have not won 44 Premier League games where they have trailed by two or more goals at half-time.
TALKING POINT: Will West Brom rue the decision to sell Shane Long?
With strikers Victor Anichebe and Saido Berahino out of form, the Baggies could have done with Long’s goals.
He is second on West Brom's leading Premier League goal scorers list with 19, only Peter Odemwingie (30) has more. So it was a strange decision to sell him in January to a relegation rival.
Long has been in good form for the Tigers and was pivotal in this win to guide them closer to safety.
MAN OF THE MATCH
Shane Long (Hull City): He may have dived to win a penalty but he kept his cool to score Hull’s second. The striker hit the post with a curling effort and his runs caused the Baggies plenty of problems.
Hull City: McGregor 7, Elmohamady 6, Chester 5, Davies 9, Rosenior 7, Aluko 5, Huddlestone 5, Livermore 5, Meyler 6, Long 9, Jelavic 6. Subs: Koren 5, Sagbo 6, Quinn 5.
West Brom: Foster 6, Reid 6, McAuley 5, Thievy 6, Dawson 5, Ridgewell 5, Dorrans 5, Mulumbu 5, Morrison 5, Sessegnon 5, Anichebe 4. Subs: Sinclair 4, Vydra 5, Berahino 5.
MATCH IN A TWEET
- Sports & Recreation
- Hull City
- West Bromwich Albion
- Liam Rosenior
- Shane Long
- David Meyler
- Nikica Jelavic
- Stephane Sessegnon