Antonyms of adj self-important

1 sense of self-important

Sense 1
arrogant, chesty, self-important -- (having or showing feelings of unwarranted importance out of overbearing pride; "an arrogant official"; "arrogant claims"; "chesty as a peacock")

INDIRECT (VIA proud) -> humble -- (marked by meekness or modesty; not arrogant or prideful; "a humble apology"; "essentially humble...and self-effacing, he achieved the highest formal honors and distinctions"- B.K.Malinowski)

Similarity of adj self-important

1 sense of self-important

Sense 1
arrogant, chesty, self-important -- (having or showing feelings of unwarranted importance out of overbearing pride; "an arrogant official"; "arrogant claims"; "chesty as a peacock")
       => proud (vs. humble) -- (feeling self-respect or pleasure in something by which you measure your self-worth; or being a reason for pride; "proud parents"; "proud of his accomplishments"; "a proud moment"; "proud to serve his country"; "a proud name"; "proud princes")