Matt Le Tissier has urged Southampton boss Ronald Koeman to sign striking reinforcements before the transfer window closes.
Tottenham will allow Emmanuel Adebayor and either Younes Kaboul or Vlad Chiriches to leave on loan before the deadline.
The club say they have paid a "substantial" undisclosed fee for the 27-year-old, who has been on loan with the Millers since October and scored four goals in 16 appearances.
Frecklington has put pen to paper on a two-and-a-half year deal after the two clubs agreed a fee earlier this week.
The transfer is subject to Football League and FA ratification.