Tizen Developers

You can wrap the label in center position to make it always center.

Evas_Object *box = elm_box_add(ad->win);
evas_object_size_hint_weight_set(box,EVAS_HINT_EXPAND,EVAS_HINT_EXPAND);
elm_object_content_set(ad->conform,box);
evas_object_show(box);

Evas_Object *label = elm_label_add(ad->conform);
elm_object_text_set(label, "Hello Tizennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn");
elm_label_wrap_width_set(label, 100);
elm_label_line_wrap_set(label,ELM_WRAP_CHAR);
//elm_label_ellipsis_set(label,true);
evas_object_size_hint_align_set(label,0.5,0.5);
evas_object_size_hint_weight_set(label, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
evas_object_show(label);
elm_box_pack_end(box,label);

You can also keep the label in center using align tag

elm_object_text_set(label, "<align=center>Hello Tizennnnnnnnnnnnnnnnnnn</align>");