He has some huge, experienced old shoes to fill but with his masterclass career at Everton, I'm sure he will do a fine job.
First thing's first for Moyes - how does he instill confidence in to the fans of Man United?
I know what you're thinking: "Bring back Ronaldo!"
Well, the transfer market is open for business and Moyes, after 11 years of tight budgets, has the cash to splash to bring in some outstanding talent.
Ezequiel Garay
With veteran centre-back Rio Ferdinand turning 35 in November coupled with the fact that Nemanja Vidic is forever injury prone, Moyes is better off hunting down a some reinforcements.
Former boss Sir Alex Ferguson identified Benfica centre-back Ezequiel Garay as a possible long-term replacement for Ferdinand.
The Argentina international has been a key figure in Benfica's Europa League success, marshalling them to the final where they narrowly lost out to Chelsea.
Gossips suggest a deal in the range of ?17million has already been agreed and his move is just a matter of agreeing personal terms.
Leighton Baines
According to The Telegraph - If Patrice Evra, now 32-years-old, leaves Old Trafford for former club Monaco, then Leighton Baines will most likely be brought in.
Baines, a loyal servant to Moyes at Everton, has been on United's radar for some time now and the opportunity to join up with his former boss might just tie up the deal.
The 28-year-old would be a fantastic addition to United's back line, he's good on the ball and specialises in set-pieces. What impresses me the most is how well he can read the game. He is rarely out of position, and if caught off guard on a counter-attack, he will give it his all to make up the ground.
Marouane Fellaini
Again, another player who might fancy joining up with his former boss and play for one of, if not, the biggest club on the planet.
The Belgian international is in-demand, with a host of clubs sniffing around, so Moyes may face something of a battle to land his signature, despite having a close link with him.
Despite what people say, Fellaini would be an excellent addition to the heart of midfield - taking some of the burden off Michael Carrick, who was at times overworked.
Fellaini's warrior attitude is something United haven't come across since Roy Keane. He's a box-to box player who also carries a huge aerial threat, making him the perfect player to lurk around the penalty area whilst Baines lines up a set-pice.
Cristiano Ronaldo
He needs no introduction, except that he is the greatest player United could ask for. So sit back and enjoy...
We'd all love to see CR7 back at Old Trafford, burning past defenders, dazzling the fans with his rapid step-overs.
Is it possible though? He has expressed his sadness at Madrid, claiming he doesn't feel appreciated by the fans.
He even denied any contract negotiations were currently in the pipeline.
But, as much as we'd love to see it, I don't see this deal happening. Something tells me it's just too complicated.
Robert Lewandowski
Lewandowski is probably at the centre of all the transfer gossip - a whole host of clubs are pushing contracts in to his face.
With Manchester United and Manchester City also keen on signing the in-demand Poland international, according to The Mirror, Chelsea are ready to "go all out" in signing him if Cavani snubs them.
He previously looked set to sign for Bayern Munich, but after the German side captured Mario Gotze, "unfairly" in Dortmund's opinion, they've refused to let Lewandowski follow him.
If you've been watching the Champions League this season, you'll know all about him.
He is strong, quick and can literally find the net from any angle.
With Rooney flirting with the possibility of leaving United, Lewandowski would be a fantastic replacement.Thiago Alcantara
According to goal.com, the Spanish starlet has agreed a deal with United, worth ?120,000 a-week.
The Barcelona midfielder has that typical Spanish style of play. He's a gifted dribbler and has Xavi-like vision when he's passing.
He'd be another great addition to the midfield, and he's still only young - which would probably, if Fellaini signed, keep him out of the team until proved his talent.
Check him out below.
The ideal XI for David Moyes?
The Defence
I've gone for the classic 4-4-2 formation as it accommodates these type of players.
I've opted for Garay over Vidic, but I'm sure Moyes will rotate the defence throughout the season.
On the bench, he has the options of Buttner, Vidic, Evans and Chris Smalling - who are all more than capable of filling in and putting in a decent shift.
The Midfield
Choosing the midfield is difficult. If this is the team for next season, then we will see United's formation change a lot.
On the bench - Alcantara, I think, will be overlooked until the youngster can prove to Moyes that he is a better option than Marouane Fellaini.
There's also the likes of Shinji Kagawa, whom would prefer a more centre-attacking-midfield role.
But, Fellaini and Carrick has a ring to it, and there it just feels like there'd be chemistry between the two.
So, Ronaldo, Fellaini, Carrick and Valencia are my picks. People may not agree with Valencia but he has my vote over Nani and Ashley Young - purely because he really gives his all.
Since his leg injury, he's struggled to get back to the form he was in when voted Manchester United's player of the year. But he's a fantastic provider of the ball, and his defensive work-rate is of a high order.
The Attack
Lewandowski and van Persie seems a match-made in heaven.
Both players have similar playing styles which might help gel the pair together.
If Rooney does choose to leave Old Trafford, Lewandowski's arrival may take the sting out of Rooney's departure.
Source: DSG
Source: DSG