As part of the association, Kapoor will endorse Lenovo's range of smartphones and will feature in various television and online commercials for the brand in India.
The youth icon already endorses Lenovo's PCs and tablets.
"Ranbir Kapoor is a multi-talented and popular actor, who is admired across the nation. We are delighted to be associated with him, as he is an extremely versatile, endearing and stylish performer just like our range of Lenovo smartphones," Lenovo India Director (Smartphones) Sudhin Mathur said.
This partnership will expand Lenovo's reach into the consumer space and enhance the preference for its smartphones in India, he added.
Lenovo ranked fifth in the tally after Samsung, Apple, Huawei and LG Electronics in smartphone sales with 4.5 per cent share of the global smartphone market in 2013, according to research firm Gartner.
In the October-December quarter of 2013, it had a global share of 4.6 per cent and ranked fourth, ahead of LG.
With a 166.8 per cent increase in the fourth quarter of 2013, India exhibited the highest smartphone sales growth, Gartner had said.
Another report estimated that the Indian smartphone market in India has grown almost three-fold to 44 million units in 2013, driven by huge uptake in sales of affordable smartphones from the stables of homegrown handset makers like Micromax and Karbonn.