The announcement said Robbins, who has held the UK COO role since March 2011, will work directly for group chief executive Philip Clarke on a number of initiatives.
Bob will work directly for me in a new role that will allow the executive team to increase its focus on the strategic priorities we have established whilst strengthening further the support we provide to the UK business, said Clarke.
Robbins sold 50,000 shares at 404.51 pence apiece on January 4, netting around 202,000 pounds, according to a filing published on January 5.
That was eight days before Tesco reported its biggest drop in underlying British sales for decades and issued a profit warning that sent its shares plunging.
Tesco said it and Robbins had operated within the rules, though the sale was criticised by corporate governance watchdogs.
A Tesco spokesman said Robbins' move was about using his skills to the best advantage of the whole business and was entirely unrelated to his share sale.
I would personally like to thank Bob for his contribution and support over the last year. His wealth of experience has improved our store operations and I look forward to working with him on delivering our strong investment plan over the coming year, said Richard Brasher, CEO, Tesco UK.
Robbins will be succeeded as UK COO by Chris Bush, the current CEO of the firm's Thailand business.
Bush, who has been at Tesco for 29 years, will be responsible for Tesco's UK stores, distribution network and leadership.
Last month we set out our determination to invest in the UK business. These changes give the UK board the combined strength of a very experienced leader of change and a talented country CEO who has done an extraordinary job in Thailand, said Brasher.
On January 12 Tesco said investment to improve its British business would hit profits in its 2012-13 financial year, sending its shares down as much as 19 percent, the biggest one-day drop since 1988.
Industry data Tuesday said UK sales growth at Tesco had slowed to just half that of the broader grocery market as rivals like Wal-Mart's Asda
John Christie, a 30-year Tesco veteran, will succeed Bush as CEO of the Thailand business.
Shares in Tesco, which have lost 21 percent of their value over the last month, were up 0.9 percent at 322.6 pence at 1137 GMT, valuing the business at about 40.53 billion pounds.
(Reporting by James Davey, Editing by Mark Potter)