Born in Finland in 1966, Kristiina graduated from the University of Industrial Arts of Helsinki (UIAH) with a Master of Arts (MA) in Design Leadership in 1992. This was followed by postgraduate studies in product development at the Helsinki University of Technology in 1993, and her second MA in Interior Architecture and Furniture Design from the UIAH in 1995.

After working in renowned interior architecture agencies in Finland and Australia she moved to Italy in 1997. She developed her first product designs for the Italian design firms Alessi, Poltronova and Zanotta.

In 2004 she founded Kristiina Lassus Studio. The Studio provides consultancy services in art direction and product design. In 2007 she registered her own trademark and introduced the Rugs Kristiina Lassus, a collection of high end hand knotted rugs. In her dual role of entrepreneur and designer she personally looks after the development and the production of each piece.

Lassus has won several international awards such as two Red Dot Awards and a Green Good Award. She has been chair of several design jurys including Fennia Prize, IF Design Award, Core Design Award and Red Dot Award.