 Ó darapọ mọ ikọ akọọkan ní sáà 200708, ó sì ṣe àríyá àkọkọ rẹ fún ikọ akọọkan Manchester United ní ọjọ 23 oṣù kẹsàn án ọdún 2008, nígbà tí ó bẹrẹ láti iwájú nínú ìfẹsẹwọnsẹ 3-1 tí wọn fi ṣẹgun Middlesbrough nínú ìdíje League Cup Third Round. Welbecks Premier League debut was made on 15 November 2008, coming on as a 63rd-minute substitute for Park Ji-sung against Stoke City. Ó kógbá wọlé fún Park Ji-sung ní ìṣẹjú kẹrìndínláàádọrin 63 nígbà tí wọn ń bá Stoke City jà. O se afihan igbohunsafẹfẹ akọkọ rẹ pẹlu ibọn ọgbọn-ọjọ ti o wa ni igun apa ọtun oke fun ibi-afẹde kẹrin ti United ni 5  0 win. Ó bẹrẹ ní : 2009 League Cup Final ni Wembley Stadium ni 1 March 2009, ninu eyi ti United ṣẹgun Tottenham Hotspur 41 lori awọn ijiya lẹhin ti 00 akoko afikun. 