The midfielder’s name had been circulated to other clubs along with Luke Rodgers and Josh Thompson by former manager Michael Appleton.
In the past week, Rodgers has joined Shrewsbury while Thompson has gone to Colchester, both on loan until January.
But Whittingham has no intention of letting Walker follow them out of the Fratton Park exit door.
The stand-in boss brought him off the bench for the final 25 minutes of Saturday’s 2-0 defeat at Bury.
It was the longest time Walker had spent on the pitch since appearing as a sub against Walsall in mid-September. And Whittingham wants the 24-year-old to remain as part of his squad as he attempts to reverse the Blues’ slide.
He said: ‘Liam will not now be going out on loan, he will get his football here.
‘He has come into a club and not played English football before so needs to learn the game.
‘It’s all right saying he is good technically, yes he is.
‘But he is one of those who maybe sometimes doesn’t move things on quick enough.
‘Having said that, he is learning all the time, he is improving all the time, and we will keep a close eye on him and try to do what’s right for him.
‘I know he did well against Gosport the other week but, no disrespect, that is four leagues below what we are doing here.
‘We know he’s a good player, we know he’s got a great left foot.
‘A couple of those balls on Saturday were inches away from being either a good ball or a shot on target – so we will keep working on him.’
Thompson was an unused substitute for Colchester in Saturday’s 3-2 loss at Crewe.
However, Rodgers was named in Shrewbury’s starting line-up in their 2-1 defeat at Leyton Orient.
The striker’s departure has raised questions considering Pompey’s shortage in that area.
And Whittingham has explained the decision.
He added: ‘Luke wants to play football and he wasn’t playing here.
‘I wasn’t going to make drastic changes on personnel and say “I’m in charge now, Luke, you are going to stay with me”.
‘I think it had also got into his head a little bit that he was going away and that chance was still there.
‘Both he and the club made the decision.
‘He still wanted to go, which is no slight on the lad because to be fair to him he has loved it here. He’s really enjoyed his time, he really appreciates the fans and he just wanted to play football.
‘That has given us the chance to bring someone in.
‘We are trying to make priorities and hopefully it will come off for us.’