On 3 February 2007 she ran the 3,000 metres indoor in Stuttgart (Germany) in a world record time of 8:23.72.

[10] She won a silver medal at the 2005 World Championships in Helsinki, losing only to Tirunesh Dibaba.

[12] She competed in the 10,000 metres event at the British national trials in July, attempting to take a spot on the Ethiopian team at the 2009 World Championships in Athletics.

[13] In Berlin, Meseret was leading the 2009 World Championships in Athletics – Women's 10,000 metres until the last 50 metres when her legs appeared to dramatically tie up, handing the gold medal to Kenya's Linet Masai and was passed by three other athletes, finishing with a time of 30:52.37.

Moving on to the road circuit, she won her third title at the Carlsbad 5000, although her time of 15:04 did not trouble her own course record.

[14] At the 2010 African Championships in Athletics, she represented Ethiopia in the 5000 m and won the silver medal behind Vivian Cheruiyot.

[15] At the beginning of 2011 she made a world record attempt for the indoor 3000 m and came just short with a run of 8:36.91 minutes.

[17] At the 2012 IAAF World Indoor Championships she aimed for a fifth straight title and was leading until the last 100 m, at which point she fell behind Hellen Obiri and finished the race as runner-up.

[18] A haul of second-place finishes followed in the outdoor season, as she came runner-up to Cheruiyot twice and fellow Ethiopian Tirunesh Dibaba.

Defar is a Christian who is a part of the Ethiopian Orthodox Tewahedo Church who exhibited her religious beliefs publicly, when celebrating her 5000 meter win at 2012 Olympics by revealing and venerating an icon of Mary and Baby Jesus.