The duo both impressed while on loan at the Banks's Stadium last season having joined on a temporary basis from Southampton and Celtic respectively.
McCarthy played every minute of every game for Whitney's side last year and ended the 2016/17 campaign being crowned Walsall's Player of the Season.
Irishman O'Connell also impressed in 17 appearances for the club after being snapped up from the Bhoys in January.
Speaking last week Whitney revealed he is already close to signing a new centre-half. But he is still interested in re-signing O'Connell as well as right-back McCarthy.
"I still want them both." the boss said.
"With Eoghan, Celtic are keeping their options open at the moment. Nothing has moved on that one yet. But I have registered my interest.
"With Jason, if we are being honest, after the season he had he is going to have several offers.
"But that goes for both of them. They are both very good players and they have got every right to go away, relax for a few weeks and then make a decision about what they want to do."
Meanwhile, Whitney wished goalkeeper Neil Etheridge the best of luck for the future after he rejected a new three-year deal with the club in favour of a move to Cardiff.
"Of course we are very disappointed to see Neil leave because he is a very good goalkeeper but he deserves his chance to go and play at a higher level," the boss added.
"I spoke to Neil Warnock (Cardiff manager) about him in January because he wanted to take him there then.
"We didn’t feel the offer was big enough for us because we were very hopeful of pushing on.
"But they always kept their interest in him and I wish him all the best.
"Neil has been really good for me. He has been a top professional and he is more than capable of going on and playing in the Championship."