She holds six outdoor and one indoor Latvian record, ranging from 3000 metres to the marathon distance. Her husband, Aleksandrs Prokopčuks, holds the men's Latvian marathon record with 2:15:56 hours. She is a three-time participant at the Summer Olympics, having represented Latvia in track events in 1996, 2000 and 2004.
Prokopčuka won the 2001 Tallinn Marathon. She won the Paris Half Marathon in 2002, 2003  and 2009. She was the 2003 champion at the World Military Cross Country Championships. She won the Great Edinburgh Run three times consecutively from 2005 to 2007. She is also a five-time winner of the Kuldīga Half Marathon, and a two-time winner of the Almond Blossom Cross Country. Elsewhere, she won the 2002 20 Kilomètres de Paris, the Osaka International Ladies Marathon in 2005 (where she ran her national record time of 2:22:56 hours), and the San Silvestre Vallecana in 2006.
She was the top-performing European at the 2012 Lisbon Half Marathon, coming fifth overall. She was tenth at the 2012 London Marathon and won the Riga Half Marathon. She surprised at the Great North Run, leading out the elite women, and although she fell to fourth she ran a national record of 68:09 minutes. Her final outing of the year came at the Yokohama Marathon, where her season's best time of 2:26:55 hours brought her fourth place.
A strong finish at the 2013 Nagoya Marathon saw her climb from 16th to fourth and record a time of 2:25:46 hours – her fastest in six years. She was runner-up to Tirunesh Dibaba at the Great Manchester Run in May.
|1994||World Junior Championships||Lisbon, Portugal||14th (h)||3000m||9:33.67|
|1997||European U23 Championships||Turku, Finland||5th||5000m||15:55.74|
|2000||Olympic Games||Sydney, Australia||9th||5000 m||14:55.46|
|2001||World Half Marathon Championships||Bristol, England||5th||Half marathon||1:08:43|
|2002||Paris Half Marathon||Paris, France||1st||Half marathon||1:11:08|
|European Championships||Munich, Germany||5th||10,000 m||31:17.72|
|World Half Marathon Championships||Brussels, Belgium||3rd||Half marathon||1:09:15|
|2003||Paris Half Marathon||Paris, France||1st||Half marathon||1:09:42|
|World Championships||Paris, France||10th||10,000 m||31:06.14|
|2004||Boston Marathon||Boston, United States||4th||Marathon||2:30:16|
|Olympic Games||Athens, Greece||7th||10,000 m||31:04.10|
|2005||World Championships||Helsinki, Finland||12th||10,000 m||31:04.55|
|New York City Marathon||New York City, United States||1st||Marathon||2:24:41|
|Osaka International Ladies Marathon||Osaka, Japan||1st||Marathon||2:22:56|
|2006||Boston Marathon||Boston, United States||2nd||Marathon||2:23:48|
|European Championships||Gothenburg, Sweden||6th||10,000 m||30:38.78|
|New York City Marathon||New York City, United States||1st||Marathon||2:25:05|
|Kuldīga Half Marathon||Kuldīga, Latvia||1st||Half marathon||1:13:36|
|2007||Boston Marathon||Boston, United States||2nd||Marathon||2:29:58|
|New York City Marathon||New York City, United States||3rd||Marathon||2:26:13|
|2008||Boston Marathon||Boston, United States||4th||Marathon||2:28:12|
|Kuldīga Half Marathon||Kuldīga, Latvia||1st||Half marathon||1:15:57|
|2009||Paris Half Marathon||Paris, France||1st||Half marathon||1:10:43|
|2010||Kuldīga Half Marathon||Kuldīga, Latvia||1st||Half marathon||1:19:30|
|2012||Riga Marathon||Rīga, Latvia||1st||Half marathon||1:10:27|
|2013||New York City Marathon||New York City, United States||3rd||Marathon||2:27:47|
|Riga Marathon||Rīga, Latvia||1st||Half marathon||1:14:39|
|2014||New York City Marathon||New York City, United States||4th||Marathon||2:26:15|
|Riga Marathon||Rīga, Latvia||1st||Half marathon||1:14:52|
|2015||Osaka International Ladies Marathon||Osaka, Japan||1st||Marathon||2:24:07|
|New York City Marathon||New York City, United States||8th||Marathon||2:28:46|
|Riga Marathon||Rīga, Latvia||1st||Half marathon||1:13:24|
|2016||Riga Marathon||Rīga, Latvia||1st||Half marathon||1:16:06|
- Evans, Hilary; Gjerde, Arild; Heijmans, Jeroen; Mallon, Bill; et al. "Jeļena Čelnova-Prokopčuka". Olympics at Sports-Reference.com. Sports Reference LLC. Archived from the original on 2012-12-15. Retrieved 2012-03-26.
- Paris Half Marathon - List of Winners
- IAAF, March 8, 2009: Prokopcuka and Worku win in Paris
- Fernandes, Antonio Manuel (2012-03-25). Tadese collects third consecutive win in Lisbon. IAAF. Retrieved on 2012-03-26.
- Wenig, Jorg (2012-09-16). Dibaba and Kipsang take Great North Run victories - REPORT. IAAF. Retrieved on 2013-01-21.
- Kizaki clinches World Championships berth with Nagoya victory as Noguchi returns. IAAF (2013-03-10). Retrieved on 2013-03-17.
- Wenig, Jörg (2013-05-26). World lead and course record for Tirunesh Dibaba over 10km in Manchester. IAAF. Retrieved on 2013-06-01.
|Wikimedia Commons has media related to Jeļena Prokopčuka.|
- Jeļena Prokopčuka at World Athletics
- Jeļena Prokopčuka at the Latvijas Olimpiskā Komiteja (in Latvian)
- Jelena Prokopcuka at the International Olympic Committee
| Latvian Women's Sportspersonality of the Year