The Sweden international became the first summer signing at Old Trafford on Wednesday after the centre-half passed a medical at Carrington training ground.
Lindelof has put pen to paper on a long-term deal with Manchester United after the Red Devils agreed a reported £30.7m move from Portuguese champions Benfica.
The 22-year-old won three Portuguese top-flight titles during a four-season stay at Benfica after moving to Portugal from Swedish outfit Vasteras SK.
And Lindelof’s beautiful blonde girlfriend Nilsson posted the above photo on her Instagram page and wrote the following caption to celebrate her parnter’s big moment.
Nilsson wrote: “PROUD ❤❤❤❤❤❤❤❤”
Manchester United secured their place in the Champions League next term after the Red Devils were 2-0 winners against Dutch giants Ajax in the Europa League final.
The 20-time English champions finished in sixth place in the Premier League table last term.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news