McGoldrick, 25, has joined on loan with a view to a permanent deal at the end of the season while Mclean, 29, has also linked up on loan until the end of the campaign.
The two players become manager Mick McCarthy's third signing during the current transfer window following the arrival of defender Patrick Kisnorbo on loan for a month from Leeds on Thursday.
McGoldrick, who started his career at Notts County and had a five-year spell at Southampton, spent the first half of the campaign on loan at Coventry, where he became the leading goalscorer in npower League One, with a total of 17 goals in 26 appearances.
Mclean began his career at Leyton Orient and after an impressive three-year spell at Peterborough moved to Hull for an undisclosed fee in December 2010.
But the forward has found it difficult to hold down a place in Steve Bruce's starting line-up this season and has been mainly restricted to a substitutes' role.
- Sports & Recreation